This **preview** has intentionally **blurred** parts. Sign up to view the full document

**Unformatted Document Excerpt**

ch17, File: Chapter 17: Scheduling True/False 1. Scheduling specifies when labor, equipment and facilities are needed to produce a product. View Full Document

Difficulty: Easy Feedback: Objectives in Scheduling 2. Scheduling is considered the last stage of the planning process. Difficulty: Easy Feedback: Objectives in Scheduling 3. The wide variety of jobs in a job shop makes scheduling difficult. Difficulty: Easy Feedback: Objectives in Scheduling 4. Managers typically use multiple objective when constructing a schedule. Difficulty: Easy Feedback: Objectives in Scheduling 5. Minimizing overtime is one of several objectives that could be considered when constructing a schedule. Difficulty: Easy Feedback: Objectives in Scheduling 6. Job shop scheduling is usually performed by skilled machine operators. Difficulty: Easy Feedback: Objectives in Scheduling 7. The process of assigning work to limited resources is known as scheduling. Difficulty: Moderate Feedback: Loading 8. Sequencing involves determining the order in which jobs are released to the shop floor. Difficulty: Hard Feedback: Sequencing 9. The sequence in which jobs should be processed is determined using linear programming. Difficulty: Moderate Feedback: Sequencing 10. Determining the optimal allocation of jobs to machines or workers can be solved using the assignment method of linear programming. Difficulty: Moderate Feedback: Sequencing 11. The process of prioritizing jobs that have been assigned to a resource is called sequencing. Difficulty: Easy Feedback: Sequencing 12. The time required for a job to move through the system is referred to as flow time. Difficulty: Moderate Feedback: Sequencing 13. All sequencing rules strive to optimize both processing efficiency and due date performance. Difficulty: Moderate Feedback: Sequencing 14. Johnsons rule gives an optimal sequence for jobs processed serially through a two step system. Difficulty: Moderate Feedback: Sequencing 15. The shortest processing time (SPT) rule is most useful when the job shop is not congested. Difficulty: Moderate Feedback: Sequencing 16. The longest processing time (LPT) rule tends to complete larger jobs in-house when subcontracting is anticipated. Difficulty: Moderate Feedback: Sequencing 17. The first-come, first-served (FCFS) sequencing rule should be only used when operating at high levels of capacity. Difficulty: Moderate Feedback: Sequencing 18. Gantt charts show the planned and yet to be completed activities against total activities. Difficulty: Moderate Feedback: Objectives in Scheduling 19. Increasing the capacity of a work center that is a bottleneck increases output. Difficulty: Moderate Feedback: Theory of Constraints 20. Finite scheduling will not load a resource beyond its fixed capacity. Difficulty: Moderate Feedback: Advanced Planning and Scheduling Systems 21. The theory of constraints (TOC) approach to scheduling concentrates on scheduling the bottleneck resources. Difficulty: Moderate Feedback: Theory of Constraints 22. With drum-buffer-rope (DBR) the bottleneck resource is always the buffer. Difficulty: Moderate Feedback: Theory of Constraints 23. Scheduling using the theory of constraints (TOC) requires that process batch sizes and transfer batch sizes always match. Difficulty: Moderate Feedback: Theory of Constraints 24. Typically, there are more options available when scheduling employees because labor is a very flexible resource. Difficulty: Moderate Feedback: Employee Scheduling 25. The scheduling function for mass production and job shop production are basically the same. Difficulty: Moderate Feedback: Objectives in Scheduling 26. Job shop scheduling is also known as shop floor control. Difficulty: Moderate Feedback: Objectives in Scheduling 27. The dispatch list contains the order in which work is assigned to a productive resource. Difficulty: Moderate Feedback: Sequencing 28. In a job shop environment the process of prioritizing jobs assigned to a productive resource is called sequencing. Difficulty: Moderate Feedback: Sequencing 29. Tardiness is defined as the difference between a jobs flow time and makespan. Difficulty: Moderate Feedback: Sequencing 30. Input/output control provides the information necessary to regulate work flow in a job shop environment. Difficulty: Moderate Feedback: Monitoring 31. The assignment method of linear programming can be used for both loading and employee scheduling. Difficulty: Moderate Feedback: Employee Scheduling Multiple Choice 32. Which of the following is not typically considered an objective of scheduling? a. minimizing job lateness b. maximizing time in the system c. minimizing overtime d. maximizing machine utilization Difficulty: Easy Feedback: Objectives of Scheduling 33. The process of assigning work to limited resources is known as a. loading. b. sequencing. c. monitoring. d. dispatching Difficulty: Easy Feedback: Loading 34. The process of prioritizing jobs that have been assigned to a resource is called a. loading. b. monitoring. c. sequencing. d. input/output analysis. Difficulty: Easy Feedback: Sequencing 35. If a job is ahead of schedule, then its critical ratio (CR) will be a. less than one. b. greater than one. c. equal to one. d. none of the above. Difficulty: Moderate Feedback: Sequencing 36. If the work remaining is greater than the time remaining, the critical ratio (CR) will be a. less than one. b. greater than one. c. equal to one. d. none of the above. Difficulty: Moderate Feedback: Sequencing 37. The time required to complete a group of jobs is referred to as a. flow time. b. makespan. c. completion time. d. none of the above. Difficulty: Easy Feedback: Sequencing 38. The sequencing rule that will minimize average job completion time for a set number of jobs to be processed on one machine is a. first-come-first served (FCFS). b. longest processing time (LPT). c. shortest process time (SPT). d. due date (DDATE). Difficulty: Moderate Feedback: Sequencing 39. The sequencing rule that minimizes average tardiness for a set of jobs to be processed on one machine is a. first-come-first served (FCFS). b. longest processing time (LPT) c. shortest process time (SPT) d. due date (DDATE). Difficulty: Moderate Feedback: Sequencing 40. If the following jobs are sequenced according to the first-come-first-served (FCFS) rule then the mean completion time in days for all jobs is (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 33 days. 22 days. 6.6 days. 4.4 days. Difficulty: Moderate Feedback: Sequencing 41. If the following jobs are sequenced according to the FCFS rule then the mean tardiness (in days) for all jobs would be (assume zero for todays date) Job Processing Time (days) A B 8 6 Due Date 12 15 C D 5 E a. b. c. d. 11 3 17 10 8 5 days. 8.33 days. 10.6 days. 25 days Difficulty: Moderate Feedback: Sequencing 42. If the following jobs are sequenced according to the FCFS rule then the maximum job tardiness (in days) is (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 0 days. 8 days. 20 days. 25 days. Difficulty: Moderate Feedback: Sequencing 43. If the following jobs are sequenced according to the FCFS rule then the total number of jobs that would be late is (assume zero for todays date) Job Processing Time (days) Due Date A B C 11 D 5 E a. b. c. d. 6 3 12 8 15 17 10 8 4. 3. 2. 1. Difficulty: Moderate Feedback: Sequencing 44. If the following jobs are sequenced according to the FCFS rule then job C is completed on day (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 11. 17. 25. 30 Difficulty: Moderate Feedback: Sequencing 45. If the following jobs are sequenced according to the SPT rule then the mean completion time (in days) for all jobs is (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 6.6 days. 16 days. 22 days. 33 days. Difficulty: Moderate Feedback: Sequencing 46. If the following jobs are sequenced according to the SPT rule then the mean tardiness (in days) for all jobs is (assume zero for todays date) Job A 5 E Difficulty: Moderate Feedback: Sequencing 11 D 16 days. 13 days. 5.2 days. 3.2 days 6 C a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 47. If the following jobs are sequenced according to the SPT rule then the maximum job tardiness (in days) is (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 26 days 16 days 10 days 5.2 days Difficulty: Moderate Feedback: Sequencing 48. If the following jobs are sequenced according to the SPT rule then the total number of jobs that would be late is (assume zero for todays date) Job A 5 E Difficulty: Moderate Feedback: Sequencing 11 D 0 jobs. 1 job. 2 jobs. 3 jobs. 6 C a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 49. If the following jobs are sequenced according to the SPT rule then job B is completed on day (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 6. 14. 15. 22 Difficulty: Moderate Feedback: Sequencing 50. If the following jobs are sequenced according to the LPT rule then the mean completion time (in days) for all jobs is (assume zero for todays date) Job A 5 E Difficulty: Moderate 11 D 118 days. 6.6 days. 33 days. 23.6 days 6 C a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 Feedback: Sequencing 51. If the following jobs are sequenced according to the LPT rule then the mean tardiness (in days) for all jobs is (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 62 days. 12.4 days. 15.5 days. 25 days Difficulty: Moderate Feedback: Sequencing 52. If the following jobs are sequenced according to the LPT rule then the maximum job tardiness (in days) is (assume zero for todays date) Job A 11 D 5 E 7 days. 10 days. 20 days. 25 days. 6 C a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 Difficulty: Moderate Feedback: Sequencing 53. If the following jobs are sequenced according to the LPT rule then the total number of jobs that would be late is (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 5 jobs. 4 jobs. 3 jobs. 2 jobs. Difficulty: Moderate Feedback: Sequencing 54. If the following jobs are sequenced according to the LPT rule then job D would be completed on day (assume zero for todays date ) Job A 6 C 11 D 5 E a. 5. b. 25. c. 30. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 d. 33. Difficulty: Moderate Feedback: Sequencing 55. If the following jobs are sequenced according to the SLACK rule then the mean completion time (in days) for all jobs is (assume zero for todays date) Job A 6 C 11 D 7 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 35 days. 20.8 days. 18.4 days. 7 days. Difficulty: Hard Feedback: Sequencing 56. If the following jobs are sequenced according to the SLACK rule then the mean tardiness (in days) for all jobs is (assume zero for todays 11.25 date) Job A 6 C 11 D 7 E a. days. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 b. 9 days. c. 20 days. d. 12.5 days. Difficulty: Hard Feedback: Sequencing 57. If the following jobs are sequenced according to the SLACK rule then the maximum job tardiness (in days) is (assume zero for todays date) Job A 6 C 11 D 7 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 20 days. 12 days. 10 days. 7 days Difficulty: Hard Feedback: Sequencing 58. If the following jobs are sequenced according to the SLACK rule then the total number of jobs that would be late is (assume zero for todays date) Job Processing Time (days) A 8 B 6 C 11 D 7 Due Date 12 15 17 10 E a. b. c. d. 3 8 1 jobs. 2 jobs. 3 jobs 4 jobs Difficulty: Hard Feedback: Sequencing 59. If the following jobs are sequenced according to the SLACK rule then job A would be completed on day (assume zero for todays date) Job A 6 C 11 D 7 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 8. 7. 15. 12. Difficulty: Hard Feedback: Sequencing 60. If the following jobs are sequenced according to the DDATE rule then the mean completion time (in days) for all jobs is (assume zero for todays date) Job Processing Time (days) A 8 B C 6 11 Due Date 12 15 17 D E a. b. c. d. 5 3 10 8 16.4 days. 22.6 days. 28.7 days. 33.0 days Difficulty: Moderate Feedback: Sequencing 61. If the following jobs are sequenced according to the DDATE rule then the mean tardiness (in days) for all jobs is (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 9.0 days. 5.4 days. 3.2 days. 2.8 days Difficulty: Moderate Feedback: Sequencing 62. If the following jobs are sequenced according to the DDATE rule then the maximum job tardiness (in days) is (assume zero for todays date) Job A Processing Time (days) 8 Due Date 12 B C 11 D 5 E a. b. c. d. 6 3 15 17 10 8 12 days. 15 days. 16 days. 27 days. Ans:: c Difficulty: Moderate Feedback: Sequencing 63. If the following jobs are sequenced according to the DDATE rule then the total number of jobs that would be late is (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 5 jobs. 4 jobs. 3 jobs. 2 jobs. Difficulty: Moderate Feedback: Sequencing 64. If the following jobs are sequenced according to the DDATE rule then job A would be completed on day (assume zero for todays date) Job A 6 C 11 D 5 E a. b. c. d. 8 B 3 Due Date Processing Time (days) 12 15 17 10 8 8. 12. 16. 22 Ans c Difficulty: Moderate Feedback: Sequencing 65. Four products (1, 2, 3, and 4) must be processed on one of four machines (A, B, C, and D). The times required in minutes for each product on each machine are shown below. Machine Product A B C D 1 10 9 16 12 2 8 14 17 5 3 19 20 11 7 4 8 18 5 10 If management wishes to assign products to machines so that the total time to complete all the products is minimized, then Product 1 is assigned to a. b. c. d. machine A machine B machine C machine D Difficulty: Hard Feedback: Sequencing 66. Four products (1, 2, 3, and 4) must be processed on one of four machines (A, B, C, and D). The times required in minutes for each product on each machine are shown below. Machine Product A B C D 1 10 9 16 12 2 8 14 17 5 3 19 20 11 7 4 8 18 5 10 If management wishes to assign products to machines so that the total time to complete all the products is minimized, then Product 3 is assigned to a. machine A. b. machine B. c. machine C. d. machine D Difficulty: Hard Feedback: Sequencing 67. Four products (1, 2, 3, and 4) must be processed on one of four machines (A, B, C, and D). The times required in minutes for each product on each machine are shown below. Machine Product A B C D 1 10 9 16 12 2 8 14 17 5 3 19 20 11 7 4 8 18 5 10 If management wishes to assign products to machines so that the total time to complete all the products is minimized, then Product 4 is assigned to a. b. c. d. machine A. machine B. machine C. machine D. Difficulty: Hard Feedback: Sequencing 68. Four products (1, 2, 3, and 4) must be processed on one of four machines (A, B, C, and D). The times required in minutes for each product on each machine are shown below. Machine Product A B C D 1 10 9 16 12 2 8 14 17 5 3 19 20 11 7 4 8 18 5 10 If management assigns products to machines so that the total time to complete all jobs is minimized, then the time to complete Product 1 is a. 10 minutes. b. 9 minutes. c. 16 minutes. d. 12 minutes Difficulty: Hard Feedback: Sequencing 69. Four products (1, 2, 3, and 4) must be processed on one of four machines (A, B, C, and D). The times required in minutes for each product on each machine are shown below. Machine Product A B C D 1 10 9 16 12 2 8 14 17 5 3 19 20 11 7 4 8 18 5 10 The minimum time required to complete all the products is a. 29 minutes. b. 27 minutes. c. 33 minutes. d. 36 minutes. Difficulty: Hard Feedback: Sequencing 70. The scheduling rule that minimizes the makespan time for a set of jobs that must be processed through a two-step system where every job follows the same sequence through the two processes is a. the shortest processing time (SPT). b. Johnsons Rule. c. the assignment method. d. the minimal slack rule. Difficulty: Easy Feedback: Sequencing 71. The following set of jobs must be processed serially through a two-step system. If Johnsons Rule is used to sequence the jobs then the order in which the jobs would be performed is Job Process 1 A 12 B 8 C 7 D 10 E 5 Process 2 9 11 6 14 8 a. b. c. d. A-B-C-D-E C-B-E-D-A E-B-D-A-C D-E-B-A-C Difficulty: Hard Feedback: Sequencing 72. The following set of jobs must be processed serially through a two-step system. The times at each process are in hours. If Johnsons Rule is used to sequence the jobs then the makespan time (in hours) for all jobs is Job A 8 C 7 D 10 E 5 Process 2 12 B a. b. c. d. Process 1 9 11 6 14 8 42 hours. 53 hours. 90 hours. 95 hours. Difficulty: Hard Feedback: Sequencing 73. The following set of jobs must be processed serially through a two-step system. The times at each process are in hours. If Johnsons Rule is used to sequence the jobs then Job C would start processing on operation 2 at Job Process 1 A 12 B C 8 7 Process 2 9 11 6 D E a. b. c. d. 10 5 14 8 hour 13. hour 26. hour 47. hour 53 Difficulty: Hard Feedback: Sequencing 74. The following set of jobs must be processed serially through a two-step system. The times at each process are in hours. If Johnsons Rule is used to sequence the jobs then Job A would complete processing on operation 2 at Job A 8 C 7 D 10 E 5 Process 2 12 B a. b. c. d. Process 1 9 11 6 14 8 hour 21. hour 35. hour 38. hour 47. Difficulty: Hard Feedback: Sequencing 75. A ________ chart is used to show both planned and completed activities against a time scale. a. Gantt b. Dispatch c. Sequencing d. None of the above. Difficulty: Easy Feedback: Monitoring Short Answer Questions 76. What makes scheduling so difficult in a job shop? Ans: Job shop scheduling is difficult because of the variety of jobs (or customers) that are processed, each with distinctive routing and processing requirements. In addition, although the volume of each customer order may be small, there are probably a great number of different orders in the shop at any one time. This necessitates planning for the production of each job as it arrives, scheduling its use of limited resources, and monitoring its progress through the system. Difficulty: Easy Feedback: Objectives in Scheduling 77. List some of the objectives in scheduling. Ans: There are many different possible objectives in constructing a schedule, including: meeting customer due dates, minimizing job lateness, minimizing response time, minimizing completion time, minimizing time in the system, minimizing overtime, maximizing machine or labor utilization, minimizing idle time, and minimizing work-inprocess inventory. Difficulty: Moderate Feedback: Objectives of Scheduling 78. Why is monitoring an important component of job shop scheduling? Ans: In a job shop environment, where jobs follow different paths through the shop, visit many different machine centers, and compete for similar resources, it is not always easy to keep track of the status of a job. When jobs are first released to the shop, it is relatively easy to observe the queue that they join and predict when their initial operations might be completed. As the job progresses, however, or the shop becomes more congested, it becomes increasingly difficult to follow the job through the system. Competition for resources (resulting in ling queues), machine breakdowns, quality programs, and setup requirements are just a few of the things that can delay a jobs progress. Monitoring develops progress reports on each job until it is completed and helps maintain reliable schedules in the system. Difficulty: Moderate Feedback: Monitoring 79. What is the difference between infinite scheduling and finite scheduling? Ans: Infinite scheduling loads work without regard to capacity and then levels the load and sequences the jobs. Thus, leveling and sequencing decisions are made after overloads and underloads have been identified. This iterative process is very time consuming and not efficient. Finite scheduling assumes a fixed maximum capacity and will not load the resource beyond its capacity. Loading and sequencing decisions are made at the same time, so that the first jobs loaded onto a work center are of highest priority. Any jobs remaining after the capacity of the work center or resource has been reached are of lower priority and are scheduled for later time periods. This approach is easier than the infinite scheduling approach, but it will be successful only if the criteria for choosing the work to be performed, as well as capacity limitations, can be expressed accurately and concisely. Difficulty: Moderate Feedback: Advanced Planning and Scheduling Systems 80. Who developed the theory of constraints (TOC) and what is its approach to scheduling? Ans: The theory of constraints (TOC) was developed by an Israeli physicist named Eliyahu Goldratt. Because he did not have a business or manufacturing background, Dr. Goldratt took a commonsense, intuitive approach to scheduling. He developed a software system that used mathematical programming and simulation to create a schedule that realistically considered the constraints of the manufacturing system. Dr. Goldratts first insight into the scheduling problem led him to simplify the number of variables considered. Instead of trying to balance the capacity of the manufacturing system, he thought it best to balance the flow of work through the system. He identified resources as bottleneck or non-bottleneck and noted that the systems flow is controlled by the bottleneck resources. These resources should always have material to work on, should spend little time on nonproductive activities, should be fully staffed, and should be the focus of continuous improvement activities. Goldratt pointed out that an hours worth of production lost at a bottleneck reduces the output of the system by the same amount of time, whereas an hour lost at a non-bottleneck resource may have no effect at all. Consequently, Goldratt simplified the scheduling problem by initially scheduling the bottleneck resources and then the non-bottleneck ones. In this way production could be synchronized with the needs of the bottleneck and the system as a whole. Difficulty: Hard Feedback: Theory of Constraints ...