ECON 41
Fall 2006
Midterm Answer Keys
Problem 1
a: A discrete variable is a variable whose values are countable (examples: the number of cars in a parking lot, the
number of people visiting a bank on any day). A continuous variable is a variable that can assume any numerical value
over a certain interval or intervals (examples: height, length, weight, and time).
b: 1: numerical facts, 2: Field or discipline of study. It consists of a group of methods used to collect,
analyze, present and interpret data and to make decisions. 3: numerical descriptive measures (example: mean,
standard deviation, and percentile) that refer to a sample
Problem 2 version A (Problem 3 version B):
(a) mean=6; mode=6; median=6;
(b) range=11; variance=7.09; standard deviation=2.66
(c) They are sample statistics because there are much more than 12 households shopping in this supermarket. These
12 households are just a sample.
If you think we are only interested in these 12 households and regard them as the population, then you have to use
the population formula in part b.
Problem 3 version A, (Problem 2 version B)
a.
P
(
they have children
)
=
380 + 140
1000
=
520
1000
b.
P
(
only one spouse works
) =
380 + 220
1000
=
600
1000
c.
P
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 Spring '07
 Guggenberger

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