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Work problems in mod 1 ch 2 exercises. Show all work.

Work problems in mod 1 ch 2 exercises.  See "NOTES" attachment for instructions.  Show all work.
2-14
A student taking Management Science 301 at East Haven University will receive one of the five possible grades fro the course: A, B, C, D, or F.  The distribution of the grades over the past two years is as follows:
Grade Number of Students
    A    80
    B    75
    C    90
    D    30
    F    25
Total               300
If this past distribution is a good indicator of future grades, what is the probability of a student receiving a C in the course?
2-16
An urn contains 8 red chips, 10 green chips, and 2 white chips.  A chip is drawn and replaced, and then a second chip is drawn.  What is the probability of
(a) a white chip on the first draw?
(b) a white chip on the first draw and a red on the second?
(c) two green chips being drawn?
(d)  a red chip on the second, given that a white chip was drawn on the first?
2-19
The Springfield Kings, a professional basketball team, has won 12 of its last 20 games and is expected to continue winning at the same percentage rate.  The team's ticket manager is anxious to attract a large crowd to tomorrow's game but believes that depends on how well the Kings perform tonight against the Galveston Comets.  He assesses the probability of drawing a large crowd to be 0.90 should the team win tonight.  What is the probability that the team wins tonight and there will be a large crowd at tomorrow's game?
2-23
Ace Machine Works estimates that the probability its lathe tool is properly adjusted is 0.8.  When the lathe is properly adjusted, there is a 0.9 probability that the parts produced pass inspection.  If the lathe is out of adjustment, however, the probability of a good part being produced is only 0.2.  A part randomly chosen is inspected and found to be acceptable.  At this point, what is the posterior probability that the lathe tool is properly adjusted?
2-26
The Northside Rifle team has two markspersons, Dick and Sally.  Dick hits a bull's-eye 90% of the time and Sally hits a bull's-eye 95% of the time.
(a) What is the probability that either Dick or Sally or both will hit the bull's-eye if each takes one shot?
(b) What is the probability that Dick and Sally will hit both the bull's-eye?
(c) Did you make any assumptions in answering the preceding questions?  If you answered yes, do you think you are justified in making the assumption(s)?
2-28
Compute the probability of "loaded die, given that a 3 was rolled," as shown in Example 7, this time using the general form of Baye's theorem from Equation 2-7.
2-31
What are the expected value and variance of the following probability distribution?
RANDOM VARIABLE X PROBABILITY
1 0.05
2 0.05
3 0.10
4 0.10
5 0.15
6 0.15
7 0.25
8 0.15
2-34
If 10% of all disk drives produced on an assembly line are defective, what is the probability there will be exactly one defect in a random sample of 5 of these?  What is the probability that there will be no defects in a random sample of 5?
2-37
An industrial oven used to cure sand cores for a factory manufacturing engine blocks for small cars is able to maintain fairly constant temperatures.  The temperature range of the oven follows a normal distribution with a mean of 450 degrees F and a standard deviation of 25 degrees F.  Leslie Larsen, president of the factory, is concerned about the large number of defective cores that have been produced in the past several months.  If the oven gets hotter than 475 degrees F. the core is defective.  What is the probability that the oven will cause a core to be defective?    What is the probability that the temperature of the oven will range from 460 degrees to 470 degrees F?
2-39
Susan Williams has been the production manager of Medical Suppliers, Inc., for the past 17 years.  Medical Suppliers, Inc., is a producer of bandages and arm slings.  During the past 5 years, the demand for No-Stick bandages has been fairly constant.  On the average, sales have been about 87,000 packages of No-Stick.  Susan has reason to believe that the distribution of No-Stick follows a normal curve, with a standard deviation of 4,000 packages.  What is the probability that sales will be less than 81,000 packages?
2-43
Patients arrive at the emergency room of Costa Valley Hospital at an average of 5 per day.  The demand for emergency room treatment at Costa Valley follows a Poisson distribution.
(a) Using Appendix C, compute the probability of exactly 0, 1, 2, 3, 4, and 5 arrivals per day.
(b) What is the sum of these probabilities, and why is the number less than 1?

Student 041201
Module 1, Ch 2, Exercises
2-14
A student taking Management Science 301 at East Haven University will
receive one of the five possible grades fro the course: A, B, C, D, or
F. The distribution of the grades over the past two years is as
follows:
Grade Number of Students
A 80
B 75
C 90
D 30
F 25
Total 300
If this past distribution is a good indicator of future grades, what is
the probability of a student receiving a C in the course?
2-16
An urn contains 8 red chips, 10 green chips, and 2 white chips. A chip
is drawn and replaced, and then a second chip is drawn. What is the
probability of
(a) a white chip on the first draw?
(b) a white chip on the first draw and a red on the second?
(c) two green chips being drawn?
(d) a red chip on the second, given that a white chip was drawn on the
first?
2-19
The Springfield Kings, a professional basketball team, has won 12 of its
last 20 games and is expected to continue winning at the same percentage
rate. The team’s ticket manager is anxious to attract a large crowd
to tomorrow’s game but believes that depends on how well the Kings
perform tonight against the Galveston Comets. He assesses the
probability of drawing a large crowd to be 0.90 should the team win
tonight. What is the probability that the team wins tonight and there
will be a large crowd at tomorrow’s game?
2-23
Ace Machine Works estimates that the probability its lathe tool is
properly adjusted is 0.8. When the lathe is properly adjusted, there is
a 0.9 probability that the parts produced pass inspection. If the lathe
is out of adjustment, however, the probability of a good part being
produced is only 0.2. A part randomly chosen is inspected and found to
be acceptable. At this point, what is the posterior probability that
the lathe tool is properly adjusted?
2-26
The Northside Rifle team has two markspersons, Dick and Sally. Dick
hits a bull’s-eye 90% of the time and Sally hits a bull’s-eye 95% of
the time.
(a) What is the probability that either Dick or Sally or both will hit
the bull’s-eye if each takes one shot?
(b) What is the probability that Dick and Sally will hit both the
bull’s-eye?
(c) Did you make any assumptions in answering the preceding questions?
If you answered yes, do you think you are justified in making the
assumption(s)?
2-28
Compute the probability of “loaded die, given that a 3 was rolled,”
as shown in Example 7, this time using the general form of Baye’s
theorem from Equation 2-7.
2-31
What are the expected value and variance of the following probability
distribution?
RANDOM VARIABLE X PROBABILITY
0.05
0.05
0.10
0.10
0.15
0.15
0.25
0.15
2-34
If 10% of all disk drives produced on an assembly line are defective,
what is the probability there will be exactly one defect in a random
sample of 5 of these? What is the probability that there will be no
defects in a random sample of 5?
2-37
An industrial oven used to cure sand cores for a factory manufacturing
engine blocks for small cars is able to maintain fairly constant
temperatures. The temperature range of the oven follows a normal
distribution with a mean of 450 degrees F and a standard deviation of 25
degrees F. Leslie Larsen, president of the factory, is concerned about
the large number of defective cores that have been produced in the past
several months. If the oven gets hotter than 475 degrees F. the core is
defective. What is the probability that the oven will cause a core to
be defective? What is the probability that the temperature of the
oven will range from 460 degrees to 470 degrees F?
2-39
Susan Williams has been the production manager of Medical Suppliers,
Inc., for the past 17 years. Medical Suppliers, Inc., is a producer of
bandages and arm slings. During the past 5 years, the demand for
No-Stick bandages has been fairly constant. On the average, sales have
been about 87,000 packages of No-Stick. Susan has reason to believe
that the distribution of No-Stick follows a normal curve, with a
standard deviation of 4,000 packages. What is the probability that
sales will be less than 81,000 packages?
2-43
Patients arrive at the emergency room of Costa Valley Hospital at an
average of 5 per day. The demand for emergency room treatment at Costa
Valley follows a Poisson distribution.
(a) Using Appendix C, compute the probability of exactly 0, 1, 2, 3, 4,
and 5 arrivals per day.
(b) What is the sum of these probabilities, and why is the number less
than 1?

Notes:
· “|” doesn't mean divide when written as P(A | B). The notation
means the “probability of A occurring given that B has occurred.”
· P(R), P(W) etc. are symbols—not functions. P(R) is the
“probability of the event R occurring.”
2-16
· b) These are independent events--each drawn chip is replaced before
the next chip is drawn. Therefore, the white chip has nothing to do with
drawing the red chip--the probability is the marginal probability of the
second event. Use equation 2-4 at the bottom of page 27
2-19
· There are two parts to this problem:
o P(W) – probability of winning
o P(L|W) – probability of large crowd tomorrow night given that the
team wins tonight.
You’re given P(L|W): P(L|W) = 0.90
And P(WL) = P(L|W) * P(W)
2-23 Bayes' Theorem (for posterior probabilities) involves conditional
probabilities. (Posterior probabilities are discussed in section 2.6.)
Bayes' Theorem:
§ What the problem is asking for is P(adjusted | pass) or P(A | B).
(note positions of A & B.)
· Need to pay attention to statements in the problem—some of the
probabilities are conditional (as needed for posterior probability):
a. Probability that the lathe is properly adjusted is 0.8 P(adjusted) =
0.8 This means that P(not adjusted) = 0.2
b. When the lathe is properly adjusted, there's a 90% probability it
will pass inspection. This is represented: P(pass | adjusted) = 0.90
c. If the lathe is out of adjustment, the probability that is good part
is being produce is only 0.2. P(pass | not adjusted) = 0.2
= "not adjusted.
§ Then replace the variables with values from the problem.
2-26
· First you must determine whether the events are mutually exclusive or
not and independent or not.
· See the "Law of Addition for Events that Are Not Mutually Exclusive"
and 2.4 "Statistically Independent Events" on pages 26-28.
o For the "either” part, see equation 2-3, Figure 2.2.
o For the "both" part, see equation 2-4, Figure 2.2
· Note: The answer in the back of text is incorrect. The correct answer
= 0.855.
2-34
· Use appropriate table.
2-37
· First Part:
o The problem asks for the probability that the oven will get hotter
than 475 degrees.
o The standard normal table gives the probability that the oven will be
less than 475 degrees
o Since the area under the curve = 1 for the standard normal curve, you
must subtract the value obtained from the table from 1.
· Second Part:
o See p-48, half-way down the page starting with, “One final
example….” through the end of the page, including Figure 2.14.
· After you obtained Z = …. standard deviations, go to the table and
retrieve a value—that value is a probability, not Z.
2-43
· Poisson Distribution equation:
= 0.0067. That holds for all P(X).
· Calculate for P(X=0), P(X=1), P(X=2), P(X=3), P(X=4), and P(X=5).
Notes:
1. 0! = 1 and 1! = 1 by definition. (See bottom of page 39.)
2. Any number to the power of zero = 1
3. Any number to the power of 1 = the starting number itself.
For X= 0, substitute the values into the equation:
Do this for X = 1, ... , 5. Show all work.
· b) Hint: The sum of all probabilities is supposed to equal 1, so why
don't these probabilities add up to one? Are there other possibilities
for arrivals?

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