Practice Questions

Practice Multiple Choice Questions for Exam 2

Prof. Alex Angelus

Sept. 20, 2014

Question 1
2.
Which of the following regarding the mean and variance of a portfolio of two stocks is false?

a. .
b. .

\

c.
d. .
2

Question 2
2.
Which of the following are required conditions for the distribution of a discrete random variable X that can assume values xi?
a. 0  p(xi)  1

for all xi

b.
c. Both a) and b) are required conditions
d. Neither a) nor b) are required conditions
3

Question 3
3.

Which of the following cannot have a Poisson distribution?

a.
b.

The length of a movie.
The number of telephone calls received by a switchboard in a specified time period.
The number of customers arriving at a gas station in
Christmas day.
The number of bacteria found in a cubic yard of soil.

c.
d.

4

Question 4
4.
The Sutton police department must write, on average, 6 tickets a day to keep department revenues at budgeted levels. Suppose the number of tickets written per day follows a Poisson distribution with a mean of 6.5 tickets per day. Interpret the value of the mean.?
a.
b.
c.
d.

The mean has no interpretation.
The expected number of tickets written would be 6.5 per day.
Half of the days have less than 6.5 tickets written and half of the days have more than 6.5 tickets written.
The number of tickets that is written most often is 6.5 tickets per day. 5

Question 5
5. Suppose f(x) = 0.25. What range of possible values can X take on and still have the density function be legitimate?
a. [0, 4]
b. [4, 8]

c. [-2, +2]
d. All of these choices are true.

6

Question 6
6. If the random variable X has a uniform distribution between 40 and 50, then P(35 ≤ X ≤ 45) is:

a.
b.
c.
d.

1.0
0.5
0.1 undefined. 7

Question 7
7. If X has a normal distribution with mean 60 and standard deviation 6, which value of X corresponds with the value z = 1.96?
a.
b.
c.
d.

x =