A) 0.451
B) 0.16
C) 0.689
D) 0.311
E) 0.9
____7. The probability model below describes the number of employees that may call in sick on any given day.
Number of sick employees
0
1
2
3
4
P(X=x)
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
C) 0.98
D) 1.31
E) 1.20
____8. 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.
____9. Given independent random variables with means and standard deviations as shown, find the mean and standard deviation of
the variable
3X - Y .
Mean
SD
X
110
15
Y
150
15
____10. Stan brings a bag of five different-colored marbles to his multiple-choice statistics test which has possible answers A through
E for each question. What is the probability Stan will get at least a 40 percent on the 20-question test if he takes a marble from the bag
at random to guess the answer for each question?
A)
3%
B)
1%
C)
15%
D)
20%
E)
40%

Homework:
____11. Which of the following events are NOT disjoint?
A. Drawing a red card that’s a spade.
B. Rolling an even number that’s prime
C. Drawing a king that’s a queen
D. All of the above
E. None of the above
____12. A student wants to watch TV. She receives 6 stations, which are broadcasting separate shows on baseball, football, basketball,
local news, national news, and international news. The student is too tired to check which channels the shows are playing, so she picks
a channel at random. The events, S and N, are defined as follows:
S = {she watches sports}
N = {she watches news}
Then, the events S and N are:
A. independent events
B. disjoint events
C. simple events
D. complementary events

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- Summer '16
- Calculus