Multiple Choice Identify the
choice that best completes the statement or answers the question.
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1.
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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 |
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2.
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A psychologist studied the number of puzzles
subjects were able to solve in a five-minute 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. |
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3.
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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. |
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4.
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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 |
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5.
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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. |
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6.
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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 |
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7.
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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 |
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8.
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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 |
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9.
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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 |
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10.
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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 |
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