7 Chapter Constraint Management
Chapter
7
Constraint Management
TRUE/FALSE
1.
A bottleneck is an operation that has the lowest effective capacity of any operation in the
process.
Answer: True
Reference: Introduction
Difficulty: Moderate
Keywords: bottleneck, effective capacity
2. The process with the least capacity is called a bottleneck if its output is less than market
demand.
Answer: True
Reference: Introduction
Difficulty: Moderate
Keywords: bottleneck, capacity
3. The process with the least capacity is called a bottleneck if its output is still greater than the
market demand.
Answer: False
Reference: Introduction
Difficulty: Moderate
Keywords: bottleneck, capacity
4. Operating processes close to their capacity can result in low customer satisfaction and even
losing money despite high sales levels.
Answer: True
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: capacity, customer satisfaction
5. The Theory of Constraints method is also referred to as the drum-buffer-rope method.
Answer: True
Reference: The Theory of Constraints
Difficulty: Easy
Keywords: TOC, theory of constraints, drum-buffer-rope
6. According to the Theory of Constraints, the four operational measures include inventory,
throughput, delivery lead times and utilization.
Answer: False
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, capacity measures, inventory, throughput, operating expense,
utilization
88
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
7. A business school with plenty of classroom space that hires adjunct faculty for a semester to
meet unusually high student demand for courses is an example of elevating a bottleneck.
Answer: True
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: elevate bottleneck, TOC
8. A bottleneck process has the lowest capacity and the longest total time from the start to the
finish.
Answer: True
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck process, lowest capacity, longest total time
9. A competent operations manager should first eliminate all of the bottlenecks from the
process.
Answer: False
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck process
10. Short term capacity planning should be driven by identification and management of
bottlenecks.
Answer: True
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: capacity planning, bottleneck
11. Line balancing is the assignment of work to stations in a line to achieve the desired output
rate with the smallest number of workstations.
Answer: True
Reference: Managing Constraints in a Line Flow Process
Difficulty: moderate
Keywords: line balance, workstations, line
12.
13.
Line balancing strives to create workstations so that the capacity utilization for the
bottleneck is much higher than for the other workstations in the line.
Answer: False
Reference: Managing Constraints in a Line Flow Process
Difficulty: moderate
Keywords: line balance, workstations, line, bottleneck
Line balancing applies only to line processes that do assembly work, or to work that can
be bundled in many ways to create the jobs for each workstation in the line.
Answer: True
Reference: Managing Constraints in a Line Flow Process
Difficulty: moderate
Keywords: line balance, workstations, line
89
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
14.
Immediate predecessors are the smallest units of work that can be performed
independently.
Answer: False
Reference: Managing Constraints in a Line Flow Process
Difficulty: Moderate
Keywords: predecessor, work, task
15.
The balance delay is the amount by which efficiency falls short of 100 percent.
Answer: True
Reference: Managing Constraints in a Line Flow Process
Difficulty: Moderate
Keywords: balance delay, efficiency
16.
To generate the maximum output, the cycle time should be set as the longest elemental
task time.
Answer: True
Reference: Managing Constraints in a Line Flow Process
Difficulty: Moderate
Keywords: cycle time, output, task
17.
Paced lines require that inventory storage areas be placed between stations.
Answer: False
Reference: Managing Constraints in a Line Flow Process
Difficulty: Moderate
Keywords: paced line, inventory
18.
A mixed-model line produces several items belonging to the same family.
Answer: True
Reference: Managing Constraints in a Line Flow Process
Difficulty: Moderate
Keywords: mixed model line, family
MULTIPLE CHOICE
19.
The focus for a process improvement exercise should be on balancing:
a. flow.
b. capacity.
c. workload.
d. time.
Answer: a
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, theory of constraints, flow
90
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
20.
According to the Theory of Constraints, the four operational measures of capacity include
all of the following EXCEPT:
a. inventory.
b. throughput.
c. utilization.
d. delivery lead times.
Answer: d
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, capacity measures, inventory, throughput, operating expense,
utilization
21.
Practical application of the Theory of Constraints involves the implementation of all of
the following steps EXCEPT:
a. Identify the system bottleneck(s).
b. Exploit the bottleneck(s).
c. Reduce the capacity at the bottleneck(s).
d. Elevate the bottleneck(s).
Answer: c
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, capacity measures, inventory, throughput, operating expense,
utilization
22.
Consider consecutive processes A-B-C, where process A has a capacity of 20 units per
hour, process B has a capacity of 25 units per hour, and process C has a capacity of 30
units per hour. Where would an operations manager want any inventory?
a. in front of process A.
b. in front of process B.
c. in front of process C.
d. inventory should not exist anywhere.
Answer: a
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, theory of constraints, inventory
23.
Use the process flow diagram to determine which of these events has the greatest net
benefit.
Station A
1 worker
8 minutes
Station B
1 worker
7 units/hr
Station C
1 worker
6 units/hr
a. reducing the flow time at Station A from 8 to 7 minutes.
b. increasing the capacity at Station B to 8 units per hour.
c. increasing the capacity at Station C to 7 units per hour.
d. reducing the flow time at Station D from 9 to 8 minutes.
Answer: c
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, theory of constraints, bottleneck
91
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Station D
1 worker
9 minutes
Chapter 7 Constraint Management
24.
Use the process flow diagram to determine which of these events has the greatest net
benefit.
Station A
1 worker
10 minutes
Station B
1 worker
10 units/hr
Station C
1 worker
8 units/hr
Station D
1 worker
12 minutes
a. reducing the flow time at Station A from 10 to 8 minutes.
b. increasing the capacity at Station B to 12 units per hour.
c. increasing the capacity at Station C to 10 units per hour.
d. reducing the flow time at Station D from 12 to 10 minutes.
Answer: d
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, theory of constraints, bottleneck
25.
Use the process flow diagram to determine which of these events has the greatest net
benefit.
Station A
1 worker
8 minutes
Station B
1 worker
10 units/hr
Station C
1 worker
8 units/hr
a. reducing the flow time at Station A from 8 to 7 minutes.
b. increasing the capacity at Station B to 12 units per hour.
c. increasing the capacity at Station C to 9 units per hour.
d. reducing the flow time at Station D from 6 to 5 minutes.
Answer: a
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, theory of constraints, bottleneck
26.
Work should be released into the system:
a. when a customer order is received.
b. when the first step in the process is idle.
c. when a customer order is completed.
d. when the bottlenecks need work.
Answer: d
Reference: The Theory of Constraints
Difficulty: Easy
Keywords: TOC, theory of constraints, bottleneck
92
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Station D
1 worker
6 minutes
Chapter 7 Constraint Management
27.
The second step in Theory of Constraints application, exploit the bottleneck(s), means
that:
a. the analyst should create a schedule that maximizes the throughput of the
bottlenecks.
b. the analyst should repeat the analysis process to look for other bottlenecks.
c. the analyst should consider increasing capacity of the bottleneck.
d. the analyst should schedule non-bottleneck resources to support the bottleneck.
Answer: a
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: bottleneck, TOC, theory of constraints
28.
The third step in Theory of Constraints application, subordinate all other decisions to
Step 2, means that:
a. the analyst should wait for authorization before proceeding with any system-wide
changes.
b. the analyst should schedule non-bottleneck processes to support the bottleneck
schedule.
c. the analyst should seek to increase capacity of only the bottleneck resources.
d. the analyst should seek to increase capacity of both the bottleneck and nonbottleneck resources.
Answer: b
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: bottleneck, TOC, theory of constraints
29.
The fourth step in Theory of Constraints application, elevate the bottleneck(s), means
that:
a. the analyst should create a schedule that maximizes the throughput of the
bottlenecks.
b. the analyst should repeat the analysis process to look for other bottlenecks.
c. the analyst should consider increasing capacity of the bottleneck.
d. the analyst should schedule non-bottleneck resources to support the bottleneck.
Answer: c
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: bottleneck, TOC, theory of constraints
30.
The fifth step in Theory of Constraints application, do not let inertia set in, means that:
a. the analyst should create a schedule that maximizes the throughput of the
bottlenecks.
b. the analyst should repeat the analysis to identify and manage new set of constraints.
c. the analyst should consider increasing capacity of the bottleneck.
d. the analyst should schedule non-bottleneck resources to support the bottleneck.
Answer: b
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: bottleneck, TOC, theory of constraints
93
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
31.
Which of the following statements regarding setups is TRUE?
a. Unusually high setup times result in higher utilization.
b. Processes are generating output throughout the entire setup process.
c. A machine used in a line process would probably have fewer setups than a batch
process.
d. A TOC analyst would not be concerned with setup times on non-bottleneck
machines.
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: setup, TOC, bottleneck
32.
There are three consecutive steps in a customer service process. The first two steps are
each capable of serving 25 customers per hour while the third step can process only 20
customers per hour. Which of the following statements regarding this system is true?
a. The entire system is capable of processing 25 customers per hour.
b. There are floating bottlenecks in the system.
c. If the first two steps are run at full capacity, then the third step has a waiting line.
d. The first and second steps are bottlenecks for the system.
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: capacity, bottleneck
Table 7.1
B
(3)
A
(4)
D
(10)
E
(2)
C
(6)
The figure above shows the call routing process for a customer service call center.
Incoming calls are routed, depending on the complexity of the callers request. Simple
request are routed to work center B, while the more complex calls are routed to work
center C (which also takes simple calls when not busy). The numbers in parentheses
are the time in minutes for each step of the process.
33.
Use the information in Table 7.1. What is the throughput time for the process, assuming
that the Call Center is always busy and has customers waiting to be processed?
a. 24 minutes
b. 18 minutes
c. 20 minutes
d. 22 minutes
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: bottleneck, throughput time
94
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
34.
Use the information in Table 7.1. What is the process bottleneck?
a. A
b. B and C together
c. D
d. E
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: process bottleneck
35.
Use the information in Table 7.1. What is the 8-hour capacity for the process?
a. 24 calls
b. 17.1 calls
c. 40 calls
d. 48 calls
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck, capacity
36.
Use the information in Table 7.1. Where would you expect customer wait times to occur?
a. D only
b. C and D
c. A only
d. E only
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck, capacity, customer wait times
95
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.2
C
(6)
A
(2)
B
(5)
E
(4)
D
(10)
The figure above shows the process for paying tuition at a major university.
Students are provided their bill for the next term for review, then routed to
different tables for questions to be answered before finally paying their tuition at
E. The numbers in parentheses are the time in minutes for each step of the
process.
37.
Use the information in Table 7.2. What is the throughput time for the A-B-C-E process
route?
a. 17 minutes
b. 27 minutes
c. 21 minutes
d. 19 minutes
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: bottleneck, throughput time
38.
Use the information in Table 7.2. What is the throughput time for the A-B-D-E process
route?
a. 17 minutes
b. 27 minutes
c. 21 minutes
d. 19 minutes
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: bottleneck, throughput time
39.
Use the information in Table 7.2. What is the capacity for the A-B-C-E process route?
a. 10 students per hour
b. 6 student per hour
c. 3.5 students per hour
d. 2.9 students per hour
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck, throughput time
96
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
40.
Use the information in Table 7.2. What is the capacity for the A-B-D-E process route?
a. 10 students per hour
b. 6 student per hour
c. 3.5 students per hour
d. 2.9 students per hour
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck, throughput time
41.
Use the information in Table 7.2. If 60% of the students are routed to C and 40% are
routed to D, what is the average capacity per hour for the process?
a. 10 students per hour
b. 6.5 student per hour
c. 8 students per hour
d. 8.4 students per hour
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: bottleneck, capacity
42.
Use the information in Table 7.2. Where would you expect student wait times to occur?
a. D only
b. B, C and D
c. A only
d. E only
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: bottleneck, capacity, customer wait times
97
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.3
A
(5)
C
(10)
D
(20)
B
(8)
E
(10)
F
(10)
G
(5)
H
(10)
The figure above shows the process for customers arriving at Pierres Spa and
Salon. After signing in, customers are routed to different locations in the Spa for the
two different services provided. The numbers in parentheses are the time in minutes
for each step of the process.
43.
Use the information in Table 7.3. What is the throughput time for the A-B-C-D -H
routing?
a. 48 minutes
b. 30 minutes
c. 53 minutes
d. 23 minutes
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: bottleneck, throughput time
44.
Use the information in Table 7.3. What is the throughput time for the A-B-E-F-G-H
routing?
a. 48 minutes
b. 30 minutes
c. 53 minutes
d. 23 minutes
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: bottleneck, throughput time
45.
Use the information in Table 7.3. What is the process bottleneck?
a. H
b. B
c. C
d. D
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck, throughput time
98
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.4
A
(5)
C
(15)
D
(20)
B
(10)
E
(30)
F
(15)
G
(10)
The figure above shows the process for customers arriving at Hobbies Unlimited for
several advertised crafts demonstrations. After signing in, customers are routed to
different locations in the store for the two different programs provided. The numbers
in parentheses are the time in minutes for each step of the process.
46.
Use the information in Table 7.4. What is the throughput time for the A-B-C-D-G
routing?
a. 25 minutes
b. 70 minutes
c. 105 minutes
d. 60 minutes
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: bottleneck, throughput time
47.
Use the information in Table 7.4. What is the throughput time for the A-B-E-F-G
routing?
a. 25 minutes
b. 70 minutes
c. 105 minutes
d. 60 minutes
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: bottleneck, throughput time
48.
Use the information in Table 7.4. How many customers can be processed through the AB-C-D-G routing during a 4-hour evening session?
a. 48
b. 24
c. 32
d. 12
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck, throughput time
99
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
49.
Use the information in Table 7.4. How many customers can be processed through the AB-E-F-G routing during a 4-hour evening session?
a. 8
b. 24
c. 12
d. 32
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: bottleneck, throughput time
Table 7.5
A company makes four products that have the following characteristics: Product A sells for
$50 but needs $10 of materials and $15 of labor to produce; Product B sells for $75 but
needs $30 of materials and $15 of labor to produce; Product C sells for $100 but needs $50
of materials and $30 of labor to produce; Product D sells for $150 but needs $75 of
materials and $40 of labor to produce. The processing requirements for each product on
each of the four machines are shown in the table.
Work Center
W
X
Y
Z
A
6
9
4
10
Processing Time (min/unit)
B
C
D
1
3
12
10
4
8
3
12
9
0
7
11
Work centers W, X, Y, and Z are available for 40 hours per week and have no setup time
when switching between products. Market demand for each product is 80 units per week. In
the questions that follow, the traditional method refers to maximizing the contribution
margin per unit for each product, and the bottleneck method refers to maximizing the
contribution margin per minute at the bottleneck for each product.
50.
Use the information in Table 7.5. Which work center is of greatest concern to the
operations manager?
a. Work center W
b. Work center X
c. Work center Y
d. Work center Z
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: TOC, bottleneck
100
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
51.
Use the information in Table 7.5. Using the traditional method, which product should be
scheduled first?
a. Product A
b. Product B
c. Product C
d. Product D
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck
52.
Use the information in Table 7.5. Using the traditional method, in what sequence should
products be scheduled for production?
a. D, C, B, A
b. D, B, A, C
c. C, D, A, B
d. C, D, B, A
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, sequence, profit per minute at bottleneck
53.
Use the information in Table 7.5. Using the traditional method, what is the optimal
product mix (consider variable costs onlyoverhead is not included in this profit
calculation)?
a. 71 A, 80B, 80C, 80 D
b. 80A, 72B, 80C, 80D
c. 80A, 80B, 60C, 80D
d. 80A, 80B, 80C, 70D
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
54.
Use the information in Table 7.5. Using the traditional method, what is the profit if the
company manufactures the optimal product mix (consider variable costs onlyoverhead
is not included in this profit calculation)?
a. Less than or equal to $8,100
b. Greater than $8,100 but less than or equal to $8,300
c. Greater than $8,300 but less than or equal to $8,500
d. Greater than $8,500
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
101
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
55.
Use the information in Table 7.5. Using the bottleneck method, which product should be
scheduled first?
a. Product A
b. Product B
c. Product C
d. Product D
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck
56.
Use the information in Table 7.5. Using the bottleneck method, in what sequence should
products be scheduled for production?
a. D. C. B. A
b. D, C, A, B
c. C, D, A, B
d. C, D, B, A
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, sequence, profit per minute at bottleneck
57.
Use the information in Table 7.5. Using the bottleneck method, what is the optimal
product mix (consider variable costs onlyoverhead is not included in this profit
calculation)?
a. 71 A, 80B, 80C, 80 D
b. 80A, 72B, 80C, 80D
c. 80A, 80B, 60C, 80D
d. 80A, 80B, 80C, 70D
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
58.
Use the information in Table 7.5. Using the bottleneck method, what is the profit if the
company manufactures the optimal product mix (consider variable costs onlyoverhead
is not included in this profit calculation)?
a. Less than or equal to $8,100
b. Greater than $8,100 but less than or equal to $8,300
c. Greater than $8,300 but less than or equal to $8,500
d. Greater than $8,500
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
102
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.6
Burdell Industries makes four different models of computer printers: the E-1000, the S-2000,
the P-2000 and the N-1000. The E-1000 sells for $200 and has $40 in parts and $40 in labor;
the S-2000 sells for $150 and requires $30 in parts and $30 in labor; the P-2000 sells for $100
and has $20 in parts and $20 in labor; and the N-1000 sells for $75 but requires only $10 of
parts and $10 of labor. Fixed overhead is estimated at $5,000 per week. The manufacture of
each printer requires four machines, Machines #1, 2, 3 and 4. Each of the machines is
available for 40 hours a week and there is no setup time required when shifting from the
production of one product to any other. The processing requirements to make one unit of each
product are shown in the table. Weekly product demand for the next planning period has been
forecasted as follows: 80 E-1000s; 65 S-2000s; 35 P-2000s; and 20 N-1000s.
Model
E-1000 (E)
S-2000 (S)
P-2000 (P)
N-1000 (N)
Processing Time (Minutes Per Printer)
Machine 1 Machine 2
Machine 3
Machine 4
10
15
15
5
10
10
10
10
5
10
15
10
5
5
5
10
In the questions that follow, the traditional method refers to maximizing the contribution
margin per unit for each product, and the bottleneck method refers to maximizing the
contribution margin per minute at the bottleneck for each product.
59.
Use the information in Table 7.6. Which machine is the bottleneck operation?
a. Machine 1
b. Machine 2
c. Machine 3
d. Machine 4
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: TOC, bottleneck
60.
Use the information in Table 7.6. Using the traditional method, which product should be
scheduled first?
a. Product E
b. Product S
c. Product P
d. Product N
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck
103
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
61.
Use the information in Table 7.6. Using the traditional method, in what sequence should
products be scheduled for production?
a. N, S, E, P
b. N, E, P, S
c. P, E, N, S
d. E, S, P, N
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, sequence, profit per minute at bottleneck
62.
Use the information in Table 7.6. Using the traditional method, what is the optimal
product mix?
a. 120 E, 90 S, 60 P, 55 N
b. 60 E, 20 S, 50 P, 33 N
c. 80 E, 65 S, 35 P, 5 N
d. 80 E, 65 S, 20 P, 35 N
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
63.
Use the information in Table 7.6. Using the traditional method, what is the profit if
Burdell manufactures the optimal product mix?
a. Less than or equal to $10,000
b. Greater than $10,000 but less than or equal to $13,000
c. Greater than $13,000 but less than or equal to $16,000
d. Greater than $16,000
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix, profit
64.
Use the information in Table 7.6. Using the bottleneck method, which product should be
scheduled first?
a. Product E
b. Product S
c. Product P
d. Product N
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck
104
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
65.
Use the information in Table 7.6. Using the bottleneck method, in what sequence should
products be scheduled for production?
a. N, S, E, P
b. N, E, P, S
c. P, E, N, S
d. E, S, P, N
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, sequence, profit per minute at bottleneck
66.
Use the information in Table 7.6. Using the bottleneck method, what is the optimal
product mix?
a. 80 E, 65 S, 35 P, 20 N
b. 60 E, 20 S, 50 P, 33 N
c. 120 E, 90 S, 60 P, 55 N
d. 80 E, 65 S, 30 P, 20 N
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
67.
Use the information in Table 7.6. Using the bottleneck method, what is the profit if
Burdell manufactures the optimal product mix?
a. Less than or equal to $10,000
b. Greater than $10,000 but less than or equal to $13,000
c. Greater than $13,000 but less than or equal to $16,000
d. Greater than $16,000
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix, profit
105
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.7
A company makes four products that have the following characteristics: Product A sells for
$75 but needs $20 of materials and $20 of labor to produce; Product B sells for $90 but
needs $45 of materials and $20 of labor to produce; Product C sells for $110 but needs $50
of materials and $30 of labor to produce; Product D sells for $135 but needs $75 of
materials and $40 of labor to produce. The processing requirements for each product on
each of the four machines are shown in the table.
Work
Center
W
X
Y
Z
A
8
12
8
10
Processing Time (min/unit)
B
C
4
9
12
9
12
10
14
5
D
10
6
5
5
Work centers W, X, Y, and Z are available for 40 hours per week and have no setup time
when switching between products. Market demand is 50 As, 60 Bs, 70 Cs, and 80 Ds per
week. In the questions that follow, the traditional method refers to maximizing the
contribution margin per unit for each product, and the bottleneck method refers to
maximizing the contribution margin per minute at the bottleneck for each product.
68.
Use the information in Table 7.7. Which work center is the bottleneck operation?
a. Work center W
b. Work center X
c. Work center Y
d. Work center Z
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: TOC, bottleneck
69.
Use the information in Table 7.7. Using the traditional method, which product should be
scheduled first?
a. Product A
b. Product B
c. Product C
d. Product D
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck
106
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
70.
Use the information in Table 7.7. Using the traditional method, in what sequence should
products be scheduled for production?
a. A, B, C, D
b. A, C, B, D
c. A, D, B, C
d. D, B, C, A
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, sequence, profit per minute at bottleneck
71.
Use the information in Table 7.7. Using the traditional method, what is the optimal
product mix?
a. 37 A, 60 B, 70 C, 80 D
b. 50 A, 51 B, 70 C, 80 D
c. 50 A, 60 B, 62 C, 80 D
d. 50 A, 60 B, 70 C, 60 D
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
72.
Use the information in Table 7.7. Using the traditional method, what is the profit if the
company manufactures the optimal product mix (consider variable costs onlyoverhead
is not included in this profit calculation)?
a. Less than or equal to $6,500
b. Greater than $6,500 but less than or equal to $6,700
c. Greater than $6,700 but less than or equal to $6,900
d. Greater than $6,900
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
73.
Use the information in Table 7.7. Using the bottleneck method, which product should be
scheduled first?
a. Product A
b. Product B
c. Product C
d. Product D
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck
107
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
74.
Use the information in Table 7.7. Using the bottleneck method, in what sequence should
products be scheduled for production?
a. A, D, B, C
b. D, A, B, C
c. A, D, C, B
d. D, A, C, B
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, sequence, profit per minute at bottleneck
75.
Use the information in Table 7.7. Using the bottleneck method, what is the optimal
product mix?
a. 37 A, 60 B, 70 C, 80 D
b. 50 A, 51 B, 70 C, 80 D
c. 50 A, 60 B, 62 C, 80 D
d. 50 A, 60 B, 70 C, 60 D
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
76.
Use the information in Table 7.7. Using the bottleneck method, what is the profit if the
company manufactures the optimal product mix (consider variable costs onlyoverhead
is not included in this profit calculation)?
a. Less than or equal to $6,500
b. Greater than $6,500 but less than or equal to $6,700
c. Greater than $6,700 but less than or equal to $6,900
d. Greater than $6,900
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
108
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.8
King Supply makes four different types of plumbing fixtures: W, X, Y and Z. The
contribution margins for these products are: $70 for Product W, $60 for Product X, $90 for
Product Y and $100 for Product Z. Fixed overhead is estimated at $5,500 per week. The
manufacture of each fixture requires four machines, Machines #1, 2, 3 and 4. Each of the
machines is available for 40 hours a week and there is no setup time required when shifting
from the production of one product to any other. The processing to requirements make one
unit of each product are shown in the table. Weekly product demand for the next planning
period has been forecasted as follows: 70 Ws, 60 Xs, 50 Ys and 30 Zs.
Fixture
W
X
Y
Z
Processing Time (Minutes Per Fixture)
Machine 1 Machine 2
Machine 3
Machine 4
10
15
10
5
5
10
15
10
20
5
5
10
15
5
5
10
In the questions that follow, the traditional method refers to maximizing the contribution
margin per unit for each product, and the bottleneck method refers to maximizing the
contribution margin per minute at the bottleneck for each product.
77.
Use the information in Table 7.8. Which machine is the bottleneck operation?
a. Machine 1
b. Machine 2
c. Machine 3
d. Machine 4
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: TOC, bottleneck
78.
Use the information in Table 7.8. Using the traditional method, which product should be
scheduled first?
a. Fixture W
b. Fixture X
c. Fixture Y
d. Fixture Z
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck
109
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
79.
Use the information in Table 7.8. Using the traditional method, in what sequence should
the fixtures be scheduled for production?
a. Z, Y, X, W
b. X, W, Z, Y
c. Z, Y, W, X
d. W, X, Y, Z
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, sequence, profit per minute at bottleneck
80.
Use the information in Table 7.8. Using the traditional method, what is the optimal
product mix?
a. 70 W, 60 X, 90 Y, 100 Z
b. 70 W, 50 X, 50 Y, 30 Z
c. 70 W, 60 X, 47 Y, 30 Z
d. 70 W, 47 X, 50 Y, 30 Z
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
81.
Use the information in Table 7.8. Using the traditional method, what is the profit if King
Supply manufactures the optimal product mix?
a. Less than or equal to $10,000
b. Greater than $10,000 but less than or equal to $11,000
c. Greater than $11,000 but less than or equal to $12,000
d. Greater than $12,000
Answer: a
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix, profit
82.
Use the information in Table 7.8. Using the bottleneck method, which product should be
scheduled first?
Fixture W
Fixture X
Fixture Y
Fixture Z
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck
a.
b.
c.
d.
110
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
83.
Use the information in Table 7.8. Using the bottleneck method, in what sequence should
products be scheduled for production?
a. Z, Y, X, W
b. X, W, Z, Y
c. Z, Y, W, X
d. X, Y, Z, W
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, sequence, profit per minute at bottleneck
84.
Use the information in Table 7.8. Using the bottleneck method, what is the optimal
product mix?
a. 70 W, 60 X, 90 Y, 100 Z
b. 70 W, 50 X, 50 Y, 30 Z
c. 70 W, 60 X, 47 Y, 30 Z
d. 70 W, 47 X, 50 Y, 30 Z
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix
85.
Use the information in Table 7.8. Using the bottleneck method, what is the profit if
Burdell manufactures the optimal product mix?
a. Less than or equal to $10,000
b. Greater than $10,000 but less than or equal to $11,000
c. Greater than $11,000 but less than or equal to $12,000
d. Greater than $12,000
Answer: b
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: TOC, bottleneck, profit per minute at bottleneck, mix, profit
86.
In a drum-buffer-rope system, the lot size that moves from one work center to another for
additional processing is a(n):
a. process batch.
b. operations batch.
c. transfer batch.
d. rope batch.
Answer: c
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: DBR, drum-buffer-rope, transfer batch
111
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
87.
The process batch at the constraint in a drum-buffer-rope system should:
a. be the same size as that at any non-constraint.
b. be the same size as the transfer batch.
c. be of such a size as to maximize the number of setups for the constraint
d. be of such a size as to improve utilization of the constraint.
Answer: d
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: DBR, drum-buffer-rope, process, batch, size
88.
Which one of the following statements is best concerning line balancing?
a. The theoretical minimum number of stations must always be fewer than the actual
number achieved in a final solution. Increasing the output rate may increase the
theoretical minimum number of stations.
b. The largest number of followers rule assigns as quickly as possible those work
elements most difficult to fit into a station.
c. Selecting the cycle time can never have an effect on line efficiency.
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: moderate
Keywords: line balancing, output rate, theoretical minimum number of work stations
89.
What is the definition of theoretical maximum efficiency?
a. It is the amount by which efficiency falls short of 100 percent.
b. It is the efficiency that could be obtained by a solution that achieves the theoretical
minimum number of stations.
c. It is the maximum time allowed for work on a unit at each station.
d. It is alternatively called the desired output rate.
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: efficiency, line process
90.
Which one of the following statements about line balancing is best?
a. If a precedence relationship exists between A and B, they cannot be assigned to the
same station.
b. If the desired output rate increases, the cycle time also tends to increase.
c. The theoretical minimum number of stations can never be achieved, hence the name
theoretical.
d. If a lines balance delay is minimized, its efficiency is maximized.
Answer: d
Reference: Managing Constraints in a Line Process
Difficulty: moderate
Keywords: line balancing, flow, balance delay, efficiency
112
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Figure 7.1
Figure 7.5
B
E
H
A
D
C
F
G
91.
Use the information in Figure 7.1. What are the required predecessors of activity H?
a. E & G
b. A through F, including E
c. Activity H has no required predecessors.
d. D
Answer: a
Reference: Managing Constraints in a Line Process
Difficulty: Easy
Keywords: predecessor, line process, flow
92.
Use the information in Figure 7.1. If each task has a work time of one minute, what is the
theoretical minimum cycle time?
a. There is no minimum cycle time.
b. 1 minute
c. 8 minutes
d. The cycle time cannot be determined with the information given.
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: cycle time, line process, flow
93.
Use the information in Figure 7.1. If each task has a work time of one minute and there
are 480 work minutes in a day, what is the task assignment at the fourth workstation if
maximum output is desired?
a. A
b. B
c. C
d. D
Answer: d
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: cycle, line process, flow, task
113
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
94.
Use the information in Figure 7.1. If each task has a work time of one minute and there
are 8 hours in a day, what is the task assignment at the first station if 160 units should be
produced each day?
a. A, B, C, D
b. H, G, F, E
c. A, B, C
d. H, G, F
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line process, flow, task, station
95.
Use the information in Figure 7.1. If each task has a work time of one minute and there
are 8 hours in a day, what is the minimum number of stations if 240 units should be
produced each day?
a. One
b. Two
c. Three
d. Four
Answer: d
Reference: Managing Constraints in a Line Process
Difficulty: moderate
Keywords: station, minimum number of stations
Table 7.9
Balance the following line for an output rate of 3 units per minute.
Work
Element
A
B
C
D
E
F
G
96.
Time
Immediate
(sec Predecessor(s)
)
12
-6
A
12
A
4
B
14
B, C
10
E
6
D, F
Use the information in Table 7.9. How many stations are required?
a. 3
b. 4
c. 5
d. 6
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: stations, flow, line process
114
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
97.
Use the information in Table 7.9. What is the balance delay for your solution?
a. Less than or equal to 15%
b. More than 15% but less than or equal to 25%
c. More than 25% but less than or equal to 35%
d. More than 35%
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: moderate
Keywords: balance delay, line process, flow
Table 7.10
Balance the following line for an output rate of five pieces per hour. The times are
in minutes (not seconds).
Work
Element
A
B
C
D
E
F
G
H
I
J
Time
Immediate
(min) Predecessor(s)
7
-5
-3
-4
-2
A, B
5
C
6
D
7
E, F
11
F, G
4
H, I
98.
Use the information from Table 7.10. The theoretical minimum number of stations is:
a. fewer than three stations.
b. three stations.
c. four stations.
d. more than four stations.
Answer: d
Reference: Managing Constraints in a Line Process
Difficulty: moderate
Keywords: line process, flow, stations
99.
Use the information from Table 7.10. The highest efficiency for a balanced line is:
a. Less than 89%.
b. More than 89% and less than 91%.
c. More than 91% and less than 93%.
d. More than 93%.
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line process, flow, efficiency
115
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.11
The Pennsylvania Appliance Company is installing an assembly line to produce vacuum
cleaners, and you, as an operations manager, are responsible for balancing the line. The
work elements to be performed are listed, along with their times and immediate
predecessors.
Work
Element
A
B
C
D
E
F
G
H
I
J
Time
(sec)
60
40
30
20
40
60
70
50
20
60
Immediate
Predecessor(s)
-A
B
B
B
C
D
F, G
E
H, I
100.
Use the information in Table 7.11. The company is planning to operate 2 shifts per day, 8
hours per shift. If the desired output rate of the line is 480 units per day, what is the cycle
time?
a. 60 seconds
b. 120 seconds
c. 180 seconds
d. 240 seconds
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: cycle time, line process, flow
101.
Use the information in Table 7.11. What is the theoretical minimum number of stations
(TM) for the line? How many workstations are needed for the most efficient balance
possible given these circumstances?
a. TM = 3; solution = 3 stations
b. TM = 3; solution = 4 stations
c. TM = 4; solution = 4 stations
d. TM = 4; solution = 5 stations
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: stations, line process, flow
116
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
102.
Use the information in Table 7.11. What is the highest efficiency possible for a balanced
line?
a. Less than 91%
b. More than 91% and less than 93%
c. More than 93% and less than 95%
d. More than 95%
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: efficiency, line process, flow
Table 7.12
A company desires to set up a line to produce 60 units per hour. The work
elements and their precedence relationships are as follows.
Work
Element
1
2
3
4
5
6
7
8
9
10
Time
(sec)
40
30
50
40
6
25
15
20
18
30
Immediate
Predecessor(s)
1
1
2
2
3
3
4,5
6,7
8,9
103.
Use the information in Table 7.12. What is the theoretical minimum number of stations?
a. 3
b. 4
c. 5
d. 6
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: minimum number of stations, line process, flow
104.
Use the information in Table 7.12. What is the highest efficiency line balance possible?
a. Less than 93%
b. More than 93% but less than or equal to 95%
c. More than 95% but less than or equal to 97%
d. More than 97%
Answer: a
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: efficiency, line process, flow
117
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.13
The following information is given about an assembly line. The desired
output rate is 90 units per hour.
Work
Element
A
B
C
D
E
F
G
H
Time
Immediate
(sec) Predecessor(s)
10
-6
A
15
A
20
B
12
B
14
C, E
8
D
20
F, G
105.
Use the information in Table 7.13. What is the fewest number of workstations that you
need?
a. Two stations
b. Three stations
c. Four stations
d. More than four stations
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: minimum number of stations, line process, flow
106.
Use the information in Table 7.13. Suppose that the desired output rate is increased to
120 units per hour and a solution has been found that has four workstations. What is the
efficiency of this new assembly line?
a. Less than 80%
b. Between 80% and 85%
c. Between 85% and 90%
d. More than 90%
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: efficiency, line process, flow
118
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
107.
A line-balancing solution has been developed for the assembly line for fertilizer spreaders
at Green Grass, Inc. The desired output rate of 30 spreaders per hour will be achieved.
The sum of times for all tasks performed on the line is 1200 seconds for each spreader
assembled. This is the total productive time. Which of the following statements must be
true?
a. The cycle time is 30 seconds per spreader.
b. The theoretical minimum number of stations is 10.
c. If the solution calls for 11 stations, the efficiency is 80%.
d. If the solution calls for 12 stations, the efficiency is 80%.
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: minimum number of stations, line process, flow
Table 7.14
The production of a particular product consists of seven work elements. The desired output
rate is 60 units per hour. The work element and their precedence relationships are given.
Work
Element
1
2
3
4
5
6
7
Time
(sec)
30
15
20
15
30
25
30
Immediate
Predecessor(s)
-1
2
3
3
4
5, 6
108.
Use the information in Table 7.14. How many stations are required for the most efficient
balance you can achieve?
a. Two stations
b. Three stations
c. Four stations
d. Five stations
Answer: b
Reference: Managing Constraints in a Line Process
Difficulty: moderate
Keywords: line process, flow, minimum number of stations
109.
Use the information in Table 7.14. What is the most efficient line balance you can
achieve?
a. Less than or equal to 70%
b. More than 70% but less than or equal to 75%
c. More than 75% but less than or equal to 80%
d. More than 80%
Answer: d
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: efficiency, line process, flow
119
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
110.
An assembly line has to perform 10 work elements, whose time requirements follow. An
operations analyst has found a solution using some heuristics, as shown in the table. If the
cycle time of the line is 90 seconds, what is the efficiency of the assembly line?
Solution
Work
Elements
Time
(sec)
A
B
C
D
E
F
G
H
I
J
45
30
15
30
50
40
30
30
60
80
Station
1
2
3
4
5
Work
Elements
Assigned
A, B, C
D, E
F, H
G, I
J
a. Less than 85%
b. Greater than 85% but less than 90%
c. Greater than 90% but less than 95%
d. Greater than 95%
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: efficiency, line process, flow
111.
Given the following data about an assembly line and the knowledge that we are trying to
attain an output rate of 40 units per hour, what is the theoretical minimum number of
stations?
Work
Element
1
2
3
4
5
6
Time
(sec)
90
80
75
70
90
85
a. Four or fewer stations
b. Five stations
c. Six stations
d. Seven or more stations
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line process, flow, minimum number of stations
120
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
112.
The production of a particular product consists of the following work elements. If the
cycle time is 4 minutes and the work-element times are as follows, what is the theoretical
minimum number of stations?
Work
Element
1
2
3
4
5
6
7
8
9
10
Time
(min)
2.4
0.5
2.1
2.0
2.7
1.1
2.0
2.7
1.6
1.4
a. Fewer than or equal to three stations
b. Four stations
c. Five stations
d. More than five stations
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line process, flow, minimum number of stations
113.
Fun Vehicles, Inc. makes beach buggies on an assembly line. The total productive time to
make one buggy is 300 seconds. The current line has a 90-second cycle time and consists
of four workstations. The balance delay of this line must be:
a. 0%.
b. greater than 0% but less than 6%.
c. greater than 6% but less than 12%.
d. greater than 12% but less than 18%.
Answer: d
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: balance delay, line process, flow
121
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
Table 7.15
The Terminal Company is attempting to balance its assembly line of high-voltage electrical
connectors. The desired output for the line is 50 connectors per hour, and the information on the
work elements for this assembly line is as follows.
Work
Elements
A
B
C
D
E
F
G
H
I
J
K
Time
(sec)
40
36
20
25
30
34
35
5
15
40
38
Immediate
Predecessor(s)
-A
A
A
B, C
D
E
F
E, H
H
G, I, J
114.
Use the information from Table 7.15 to balance this line. What is the most efficient
solution?
a. More than 90%
b. 8090%
c. 7079%
d. Less than 70%
Answer: c
Reference: Managing Constraints in a Line Process
Difficulty: Hard
Keywords: efficiency, line balance, flow
115.
Use the information from Table 7.15 and the most efficient line balance possible. What
work elements are included in the first station?
a. A only
b. A and B only
c. A and E only
d. A and D only
Answer: d
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: tasks, station, line balance, flow
122
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
116.
Use the information from Table 7.1 5, and assume that the most efficient line balance
possible ha been achieved. What is the total idle time for an eight hour work day?
a. Less than an hour and a half.
b. More than 1:30 but less than or equal to 1:45.
c. More than 1:45 but less than or equal to 2 hours.
d. More than 2 hours
Answer: d
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: idle time, line balance, flow
FILL IN THE BLANK
117.
A(n) ____________ is an operation that has the lowest effective capacity of any
operation in the process, and thus limits the systems output.
Answer: bottleneck
Reference: The Theory of Constraints
Difficulty: moderate
Keywords: bottleneck, TOC, output
118.
____________ is the total time taken from the start to the finish of a process.
Answer: Throughput time
Reference: Identification and Management of Bottlenecks
Difficulty: Easy
Keywords: throughput time
119.
Variability of a firms workload may create ____________.
Answer: floating bottlenecks
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: workload, variability, floating bottleneck
120.
With TOC, ____________ are scheduled to maximize their throughput of products while
adhering to promised completion dates.
Answer: bottlenecks
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: TOC, bottleneck
121.
Instead of producing products with the highest profit margins, operations managers
should focus on the ____________ generated at the ____________ .
Answer: profit (margin), bottleneck
Reference: Identification and Management of Bottlenecks
Difficulty: Moderate
Keywords: TOC, bottleneck, profit, profit margin
123
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
122.
____________ is a planning and control system that regulates the flow of work-inprocess materials at the bottleneck or the capacity constrained resource in a productive
system.
i) Answer: Drum-buffer-rope (DBR)
ii) Reference: Identification and Management of Bottlenecks
iii) Difficulty: Easy
iv) Keywords: drum-buffer-rope, DBR, CCR, capacity constrained resource, bottleneck
123.
Every time a manufacturer uses one resource, they make a lot size of 300. Once a group
of 30 units are completed, they are taken to the next step in the process. The lot of 300 is
the ____________ and the group of 30 is the ____________.
i) Answer: production batch, transfer batch
ii) Reference: Identification and Management of Bottlenecks
iii) Difficulty: Moderate
iv) Keywords: production batch, transfer batch
124.
____________ is the maximum time allowed for work on a unit at each station.
Answer: Cycle time
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: cycle time, work, line process, flow
125.
____________ is the amount by which efficiency falls short of 100 percent.
Answer: Balance delay
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: balance delay, efficiency, line process, flow
126.
Regardless of the number of tasks or their lengths, a line balance efficiency of 100% is
possible if the number of stations is ____________.
Answer: one
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line balance, efficiency
127.
A(n) ____________ line is a product line that produces several items belonging to the
same family.
Answer: mixed-model
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: mixed-model line, family
128.
The movement of product from one station to the next as soon as the cycle time has
elapsed is called ____________.
Answer: pacing
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: pacing, line process, flow, cycle time
124
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
SHORT ANSWERS
129.
Explain why a bottleneck limits system output.
Answer: A bottleneck, by definition, is a process that has less capacity than all other
processes in the system. Just as a chain is as strong as its weakest link, the rest of a
production system can produce only as much as the slowest process. The bottleneck
limits capacity by serving to slow the rest of the system down. Running all other
processes at their maximum capacity will result in inventory buildup in front of the
bottleneck.
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: bottleneck, output, TOC
130.
Describe a process from your own personal experience at home or work that suffers from
a lack of sufficient throughput. Apply the first four TOC steps to address the situation,
assuming you have complete authority to do so.
Answer: Examples will vary. The steps of TOC are (1) identify the system bottleneck(s);
(2) exploit the bottlenecks; (3) subordinate all other decisions to step 2; (4) elevate the
bottleneck(s); and (5) do not let inertia set in.
Reference: The Theory of Constraints
Difficulty: Moderate
Keywords: TOC, steps
131.
Describe three ways that line balancing and line flow layouts are similar to project
management and three ways they are different.
Answer: Answers may vary. Line balancing and project management both rely on the
completion of predefined activities in the proper sequence. A line flow may have multiple
feeder lines that supply subassemblies to the main line, similar to subcontractors working
on the project in state of partial completion. Both have anticipated completion times that
may not be reached if things dont go smoothly.
The time scale is radically different between line balancing and project management;
projects tend to take much longer. Projects also tend to be one of a kind endeavors; line
balancing is performed with the anticipation of high volumes of fairly standardized
output. Line flows are created for more routine, process-oriented work that can be
composed of standardized tasks. Projects are typically anything but routine and far from
process-focused.
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line balancing, flow layout
125
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
132.
How can Theory of Constraints principles be reconciled with line balancing?
Answer: Line balancing strives to assign work to stations such that the amount of work
at each station is equal. Work flows from station to station based on a cycle time that is
determined based on the number of units to be produced per unit time. Theory of
Constraints stresses the need to balance flow with demand and is concerned with
preserving flow through the bottleneck, or lowest capacity station. Flow can be preserved
by protecting the bottleneck with protective WIP and making sure that market demand is
sufficient to support continuous bottleneck operation. Line balancing, as explained in the
text, assumes that all task times are constant. So the person performing the balance can
try to allocate capacity as evenly as possible. If task times were stochastic, then flow
would not be preserved with classic line balancing techniques because the lowest
capacity work station would occasionally fall idle.
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line balancing, TOC, theory of constraints
126
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
PROBLEMS
133.
Schmidt Industries makes four different snake traps; the Harlan, the Gaylen, the Leah and
the Matthew. The Harlan sells for $200 and has $40 in parts and $40 in labor; the Gaylen
sells for $150 and requires $30 in parts and $30 in labor; the Leah sells for $100 and has
$20 in parts and $20 in labor; and the Matthew sells for $75 but requires only $10 of parts
and $10 of labor. Schmidt Industries has four machines (well call them A, B, C, and D
for convenience) that are used in the production of each of these products. Each of these
machines is available for 40 hours a week and there is no setup time required when
shifting from the production of one product to any other. The processing requirements to
make one unit of each product are shown in the table.
Model
Harlan
Gaylen
Leah
Matthew
Processing Time on Each Machine in Minutes
Machine A Machine B Machine C Machine D
10
15
15
5
10
10
10
10
5
10
15
10
5
5
5
10
Schmidt Industries has monthly fixed costs of $5000 and has a demand forecast of 80
Harlans, 60 Gaylens, 40 Leahs and 20 Matthews for the coming month. How many of each of
the four models should Susan, the operations manager, schedule for production this month?
Answer:
The processing requirements for the demand forecast result in a need for:
Machine A : 80 10 + 60 10 + 40 5 + 20 5 = 1700 2400
Machine B : 80 15 + 60 10 + 40 10 + 20 10 = 2300 2400
Machine C : 80 15 + 60 10 + 40 15 + 20 10 = 2500 2400 Bottleneck
Machine D : 80 5 + 60 10 + 40 10 + 20 10 = 1600 2400
The contribution margin per bottleneck minute is:
Harlan : (200 - 40 - 40)/15 = $8/min
Gaylen : (150 - 30 - 30)/10 = $9/min
Leah : (100 - 20 - 20)/15 = $4/min
Matthew : (75 - 10 - 10)/5 = $11/min
Products should be produced in Matthew, Gaylen, Harlan, and Leah order. The product
mix is 20 Matthews (using 100 minutes of Machine C); 60 Gaylens (using 600 minutes of
Machine C); 80 Harlans (using 1200 minutes of Machine C); and 33 Leahs (using up the
remaining 500 minutes of Machine C time)
Reference: Identification and Management of Bottlenecks
Difficulty: Hard
Keywords: capacity, bottleneck
127
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
134.
Consider the process shown that is trying to produce to meet a market demand of 500
units per week.
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 1: Material release schedule
Step 2: Drilling (capacity is 500 units/week)
Step 3: Tapping (capacity is 450 units/week)
Step 4: Grinding (capacity is 600 units/week)
Step 5: Coating (capacity is 400 units/week)
Step 6: Inspection (capacity is 1000 units/week)
a.
b.
c.
d.
e.
i)
ii)
iii)
Where should buffers be placed?
Which resource is the drum?
Where should the rope be placed?
Which resource is the bottleneck?
Which resource is the CCR?
Answer:
a. A constraint buffer should be placed between steps 4 and 5 to protect the
bottleneck which is Step 5 (Coating). A shipping buffer should be placed at the end
of the line, after Step 6,(Inspection).
iv) b. The resource functioning as the drum is the bottleneck, Step 5.
v) c. The rope should connect Step 1 and Step 5.
vi) d. The bottleneck is Step 5.
vii) e. A CCR exists if the process with the least capacity can still meet market demand,
which is not the case in this scenario.
viii) Reference: Managing Constraints in a Line Process
ix) Difficulty: Moderate
x) Keywords: drum-buffer-rope, DBR, CCR, capacity constraint resource, bottleneck
128
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
135.
Balance the assembly line for the tasks contained in the table. The desired output is 240
units per day. Available production time per day is 480 minutes. What is the efficiency
for the balanced assembly line?
Work Element Time (Sec.) Immediate Predecessor(s)
A
40
--B
45
--C
55
A
D
55
B
E
65
B
F
40
C,D
G
25
D,E
Answer:
For 240 units/day with available time of 480 minutes per day, the cycle time is 2.00
minutes or 120 seconds.
One line balance is:
Station
Task(s)
Work Time
Idle Time
Efficiency =
1
B, E
45, 65
10
2
D, A
55, 40
25
3
Totals
C, F, G
55, 40, 25 325
0
35
Work Time
325
=
= 90.28%
Work Time + Idle Time 325 + 35
There are four other legal assignments possible at the first work station, AB, BA, AC,
and BD. There are a large number of possible legal balances since the longest two task
times sum to 120, which is within the desired cycle time. A number of possible balances
will achieve the three station balance that yields 90.28% efficiency.
Reference: Managing Constraints in a Line Process
Difficulty: moderate
Keywords: line balance, efficiency
129
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
136.
Balance the assembly line using the following task information contained in the table.
The desired output is 360 units per day. Available production time per day is 480
minutes. What is the efficiency for the balanced assembly line?
Work Element
A
B
C
D
E
F
G
H
Time (Sec.)
30
20
50
45
30
55
35
40
Immediate Predecessor(s)
--A
A
B
B
C,D
D,E
F
Answer:
Cycle time for 360 units in a 480 minute day is 480/360 = 1.33 minutes = 80 seconds
The theoretical minimum number of stations is 4; this balance is one of the 5 station
solutions.
Station
1
2
3
4
5
Totals
Task(s)
A, C
B, D
F
H, E
G
Work Time
30, 50
20, 45
55
40, 30
35
305
Idle Time
0
15
25
10
45
95
Efficiency =
Work Time
305
=
= 76.25%
Work Time + Idle Time 305 + 95
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line balance, efficiency
130
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 7 Constraint Management
137.
Balance the line in order to achieve maximum output for this ten activity product.
Determine the number of units produced in a seven hour work day and the total idle time
in hours.
Task
Z
Y
X
W
V
T
S
R
Q
M
Time (sec)
40
30
80
75
15
55
35
40
10
40
Predecessor
--Z
Z
X, Y
W
W
V
T
R
S, R
Answer:
Cycle time for maximum output is 80 seconds and the theoretical minimum number of
stations is
Station
Task(s)
Work Time
Idle Time
Efficiency =
1
Z, Y
40, 30
10
2
X
80
0
3
W
75
5
4
V, T
15,55
10
5
S
70
10
6
R, M
40, 40
0
7
Q
60
20
Totals
420
55
Work Time
420
=
= 88.42%
Work Time + Idle Time 420 + 55
There are 315 units produced in a day.
7 hours / day60 minutes60 seconds
80 seconds / unit
The total idle time per day at this level of production is 4.8125 hours. (4:48:45 to be
precise)
315 units/day 55 seconds idle/unit = 17,325 seconds
17,325 seconds
= 4.8125 hours
3600 seconds/hour
Reference: Managing Constraints in a Line Process
Difficulty: Moderate
Keywords: line balance, efficiency
131
Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall