Solutions – Homework 1
2.3 Identify the variable type:
a) quantitative
b) categorical
c) categorical
d) quantitative
2.6 Discrete or continuous?:
a) continuous
b) discrete
c) continuous
d) discrete
2.8 Number of children:
a) The variable, number of children, is quantitative.
b) The variable, number of children, is discrete.
c)
No. children
0
1
2
3
4
5
6
7
8+
Count
1216
710
1147
738
386
139
83
43
35
Proportion
0.270
0.158
0.255
0.164
0.086
0.031
0.018
0.010
0.008
Percentage
27.0
15.8
25.5
16.4
8.6
3.1
1.8
1.0
.8
d) The mode – the most common score – is 0.
2.10 What do alligators eat?
:
a) Primary food choice is categorical.
b) The mode is “fish.”
c) A little over 40% of alligators ate fish as their primary food choice.
d) This is an example of a Pareto chart, a chart that is organized from most to least frequent choice.
2.15 eBay prices:
a)
17  8
18 
19  9
20  0
21  00
22  55558
23  25
24  00056669
25  00055
b) This plot gives us an overview of all the data. We see clearly that the prices fall between $178 and
$255,
with more PDAs selling at the upper end of this range.
2.23 Shape of the histogram:
a) Assessed value houses in a large city – skewed to the right because of some very expensive homes
b) Number of times checking account overdrawn in the past year for the faculty at the local university –
skewed to the right because of the few faculty who overdraw frequently
c) IQ for the general population – symmetric because most would be in the middle, with some higher and
some lower; there’s no reason to expect more to be higher or lower (particularly because IQ is constructed
as a comparison to the general population’s “norms”)
d) The height of female college students – symmetric because most would fall in the middle, going down
to a few short students and up to a few tall students
1
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2.25 How often do students read the newspaper?
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 Spring '11
 Thomas
 Standard Deviation, Mean, unemployment rates, $255

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