Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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1.
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An assignment of probability must obey which of the
following?
a. | The probability of any event must be a number between 0
and 1, inclusive. | b. | The sum of all the
probabilities of all outcomes in the sample space must be exactly 1. | c. | The probability of an event is the sum of the outcomes in the sample space
which make up the event. | d. | All of the
above. | e. | A and B only. |
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2.
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Students at University X must be in one of the
class ranks—freshman, sophomore, junior, or senior. At University X, 35% of the students are
freshmen and 30% are sophomores. If a student is selected at random, the probability that her or she
is either a junior or a senior is
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In a particular game, a fair die is tossed. If the
number of spots showing is either four or five, you win $1. If the number of spots showing is six,
you win $4. And if the number of spots showing is one, two, or three, you win nothing. You are going
to play the game twice.
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3.
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The probability that you win $4 both times
is
a. | 1/6 | b. | 1/3 | c. | 1/36 | d. | 1/4 | e. | 1/12 |
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4.
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The probability that you win money at least once in
the two games is
a. | .75 | b. | .50 | c. | .25 | d. | .125 | e. | .1 |
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An event A will occur with probability 0.5.
An event B will occur with probability 0.6. The probability that both A and B
will occur is 0.1.
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5.
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The conditional probability of A given
B is
a. | 0.5. | b. | 0.3. | c. | 0.2. | d. | 1/6. | e. | cannot be
determined from the information given. |
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6.
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Experience has shown that a certain lie detector
will show a positive reading (indicates a lie) 10% of the time when a person is telling the truth and
95% of the time when a person is lying. Suppose that a random sample of 5 suspects is subjected to a
lie detector test regarding a recent one-person crime. Then the probability of observing no positive
reading if all suspects plead innocent and are telling the truth is
a. | 0.409 | b. | 0.735 | c. | 0.00001 | d. | 0.590 | e. | 0.99999 |
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7.
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If you buy one ticket in the Provincial Lottery,
then the probability that you will win a prize is 0.11. If you buy one ticket each month for five
months, what is the probability that you will win at least one prize?
a. | 0.55 | b. | 0.50 | c. | 0.44 | d. | 0.45 | e. | 0.56 |
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8.
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Suppose that A and B are two independent events
with P(A) = .2 and P(B) = .4.
P(A Ç
Bc) is
a. | 0.08. | b. | 0.12. | c. | 0.52. | d. | 0.60. |
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9.
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A plumbing contractor puts in bids in on two large
jobs. Let the event that the contractor wins the first contract be A and the event that the
contractor wins the second contract be B. Which of the Venn diagrams has shaded the event that the
contractor wins exactly one of the contracts?
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10.
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A die is loaded so that the number 6 comes up three
times as often as any other number. What, then, is the probability of rolling a
6?
a. | .125 | b. | .250 | c. | .375 | d. | .500 | e. | None of the
above. |
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