Transcript Ch. 14-16 Review

1) If P(A) = 0.24 and P(B) = 0.52 and events A and B are
independent, what is P(A or B)?
A)0.1248
B) 0.2800
C) 0.7600
D) 0.6352
E) The answer cannot be determined from the information
given.
2. Which of the following pairs of events, A and B, are disjoint
(mutually exclusive)?
A) A  the odd numbers; B  the number 5
B) A  the even numbers; B  the numbers greater than 10
C) A  the numbers less than 5; B  all negative numbers
D) A  the numbers above 100; B  the numbers less than -200
E) A  negative numbers; B  odd numbers
3) Shameel has a flight to catch on Monday morning. His father
will give him a ride to the airport. If it rains, the traffic will be bad
and the probability that he will miss his flight is 0.05. If it doesn't
rain, the probability that he will miss his flight is 0.01. The
probability that it will rain on Monday is 0.18.
Suppose that Shameel misses his flight. What is the probability
that it was raining?
A) 0.477
B) 0.523
D) 0.05
E) 0.18
C) 1.098
Some employers use lie detector tests to screen job applicants. Lie detector
tests are not completely reliable. Suppose that a polygraph can detect 65% of
lies, but incorrectly identifies 16% of true statements as lies.
A company gives its job applicants a polygraph test, asking "Did you tell the
truth on your job application?". All the applicants answer "Yes", but the test
identifies some of those answers as lies, thereby causing the person to fail the
test.
Suppose that 90% of the job applicants tell the truth during the polygraph test.
What is the probability that a person who fails the test was actually telling the
truth?
A) 0.451
B) 0.16
D) 0.311
E) 0.9
C) 0.689
5) You pick a card from a deck. If you get a club, you win $90. If
not, you get to draw again (after replacing the first card). If you get
a club the second time, you win $30. If not, you lose.
Find the expected amount you will win.
A) $30.00
B) $32.34
D) $45.00
E) $28.13
C) $36.56
6) Sue Anne owns a medium-sized business. The probability
model below describes the number of employees that may call in
sick on any given day.
Number of sick
employees
P(X=x)
0
1
2
3
4
0.05
0.4
0.25
0.2
0.1
What is the standard deviation of the number of employees
calling in sick each day?
A)1.19
B) 1.09
D) 1.31
E) 1.20
C) 0.98
7) A company sells light bulbs in packages of 20 and
estimates that the mean number of defective light bulbs in a
package is 0.5 with a standard deviation of 0.7. If a
customer buys 12 packages, what are the expected value
and standard deviation of the number of defective light
bulbs? Assume that packages are independent of each
other.
A) μ = 6, σ = 2.42
B) μ = 1.73, σ = 2.42
C) μ = 6, σ = 100.8
D) μ = 6, σ = 8.4
E) μ = 1.73, σ = 8.4
8) Given independent random variables with means and standard deviations as
shown, find the mean and standard deviation of the variable 3X - Y .
X
Y
Mean
110
150
SD
15
15
A) μ = 180, σ = 47.43
B) μ = 180, σ = 42.43
C) μ = 180, σ = 30
D) μ = 480, σ = 47.43
E) μ = -120, σ = 30
9) You pick a card from a deck. If you get a face card, you win
$15. If you get an ace, you win $25 plus an extra $40 for the ace
of hearts. For any other card you win nothing.
Create a probability model for the amount you win at this game.
1)C
2) D
Review – Multiple Choice
3)B
4) C
5)E
6) B
7) A
8) A
Chapters 14, 15 and 16