Kata Bognar
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Economics 41
Statistics for Economists
UCLA
Spring 2010
Final Exam
 answer key 
Part I  Multiple Choice Questions (3 points each)
1. A statistician wants to determine the total annual medical costs incurred by all U.S. states from
1981 to 2001 as a result of health problems related to smoking. She polls each of the fifty states
annually to obtain health care expenditures, in dollars, on smokingrelated illnesses. Which one
of the following is NOT a true statement?
C
(a) The population is all U.S. states.
(b) The sample is the same as the population.
(c)
The data collected are qualitative data.
(d) You can consider each state as an element of the study.
2. A research team conducts an experiment on an automotive plant to determine the effect of pro
duction demands on stress levels. Which one of the following describes the drawing of a random
sample of all paid employees of the plant?
A
3. The value that occurs with a maximum frequency in a data set is the:
C
Explanation
: See the definition of mode in the book.
4. Suppose that there are 10 songs on a CD and you like 6 of them. When you choose shuffle on the
CD player each of the 10 songs is played once in a random order. The probability that you like
both of the first two songs played is
A
)
= 45 ways in which any first two songs can be selected and there
are
(
6
2
)(
4
0
)
= 15 ways in which first two songs that you like can be selected. The probability is the
ratio of these two: 15
/
45 = 1
/
3
.
5. Which of the following is true?
B
(a)
∑
5
i
=1
i
= 10
(b)
5
C
2
=
10
(c)
5
P
2
= 10
1
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(d) 5! = 10
Explanation:
∑
5
i
=1
i
= 1 + 2 + 3 + 4 + 5 = 15
5
C
2
=
5
·
4
2
= 10
5
P
2
= 5
·
4 = 20
5! = 5
·
4
·
3
·
2
·
1 = 120
.
6. A random variable X that takes on four different values has the following distribution:
P
(
X
=

1) =
a,
P
(
X
= 0) =
b, P
(
X
= 1) = 0
.
4 and
P
(
X
= 2) = 0
.
1
.
The expected value of
X
is 0
.
2. The value
of the constants
a
and
b
are:
D
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 Fall '07
 Guggenberger
 Economics, Normal Distribution, Standard Deviation, researcher

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