Multiple Choice Identify the
choice that best completes the statement or answers the question.


1.

Which of the following random variables should be
considered continuous?
a.  The number of CD’s a randomly chosen person
has  b.  The number of sisters a randomly chosen person
has  c.  The number of goals scored in a randomly chosen soccer
game  d.  The number of tacos ordered by a randomly chosen Del
Taco customer.  e.  None of the
above 


2.

A psychologist studied the number of puzzles
subjects were able to solve in a fiveminute period while listening to soothing music. Let X be
the number of puzzles completed successfully by a subject. X had the following
distribution:
X
1 2 3 4
Probability 0.2 0.4
0.3 0.1
Using the above data, the mean
µ of X is
a.  2.0  b.  2.3  c.  2.5  d.  3.0  e.  The answer cannot
be computed from the information given. 


3.

A random variable X has a probability distribution
as follows:
X 0
1 2 3_
P(X) 2k
3k 13k 2k Then the probability that P(X = 2)
is equal to
a.  0.90.  b.  0.25.  c.  0.65.  d.  0.15.  e.  1.00. 


4.

Suppose X is a random variable with mean
µ. Suppose we observe X many times and keep track of the average of the observed
values. The law of large numbers says that
a.  The value of µ will get larger and larger as we
observe X.  b.  As we observe X
more and more, this average and the value of µ will get larger and
larger.  c.  This average will get closer and closer to µ as we
observe X more and more often.  d.  As we observe X
more and more, this average will get to be a larger and larger multiple of
µ.  e.  None of the above 


5.

A factory makes silicon chips for use in
computers. It is known that about 90% of the chips meets specifications. Every hour a
sample of 18 chips is selected at random for testing. Assume a binomial distribution is
valid. Suppose we collect a large number of these samples of 18 chips and determine the number
meeting specifications in each sample. What is the approximate mean of the number of chips
meeting specifications?
a.  16.20  b.  1.62  c.  4.02  d.  16.00  e.  The answer cannot
be computed from the information given. 


6.

Twenty percent of all trucks undergoing a certain
inspection will fail the inspection. Assume that trucks are independently undergoing this
inspection, one at a time. The expected number of trucks inspected before a truck fails
inspection is
a.  2  b.  4  c.  5  d.  20  e.  The answer cannot
be computed from the information given 


7.

Two percent of the circuit boards manufactured by a
particular company are defective. If circuit boards are randomly selected for testing, the
probability it takes 10 circuit boards to be inspected before a defective board is found
is
a.  .0167  b.  .9833  c.  0.1829  d.  0.8171  e.  The answer cannot
be computed from the information given 


8.

Two percent of the circuit boards manufactured by a
particular company are defective. If circuit boards are randomly selected for testing, the
probability that the number of circuit boards inspected before a defective board is found is greater
than 10 is
a.  1.024 ´
10^7  b.  5.12 ´
10^7  c.  0.1829  d.  0.8171  e.  The answer cannot
be computed from the information given 


9.

It has been estimated that about 30% of frozen
chickens contain enough salmonella bacteria to cause illness if improperly cooked. A consumer
purchases 12 frozen chickens. What is the probability that the consumer will have exactly 6
contaminated chickens?
a.  0.961  b.  0.118  c.  0.882  d.  0.039  e.  0.079 


10.

It has been estimated that about 30% of frozen
chickens contain enough salmonella bacteria to cause illness if improperly cooked. A consumer
purchases 12 frozen chickens. What is the probability that the consumer will have more than 6
contaminated chickens?
a.  0.961  b.  0.118  c.  0.882  d.  0.039  e.  0.079 
