Solutions
55
1.8.
This histogram shows more details about
the distribution (perhaps more detail than
is useful). Note that this histogram has the
same shape as the Frst histogram in the
solution to Exercise 1.6.
55
60
65
70
75
80
85
90
95
100
0
1
2
3
4
5
6
7
Frequency
First exam scores
1.9.
Using either a stemplot or histogram, we see that the distribution is left-skewed, centered
near 80, and spread from 55 to 98. (Of course, a histogram would not show the exact values
of the maximum and minimum.)
1.10.
Recall that categorical variables place individuals into groups or categories, while
quantitative variables “take numerical values for which arithmetic operations
...
make sense.”
Variables (a), (d), and (e)—age, amount spent on food, and height—are quantitative. The
answers to the other three questions—about dancing, musical instruments, and broccoli—are
categorical variables.
1.13.
Possible responses would include heart rate before and after exercise (typically measured
with a watch and Fngertip), number of sit-ups (no instrument required), time to run 100 m
(measured with a stopwatch).
1.14.
Student answers will vary. Recent rankings in
U.S. News and World Report
used
“16 measures of academic excellence,” including academic reputation (measured by
surveying college and university administrators), retention rate, graduation rate, class
sizes, faculty salaries, student-faculty ratio, percentage of faculty with highest degree
in their Felds, quality of entering students (ACT/SAT scores, high school class rank,
enrollment-to-admission ratio), Fnancial resources, and the percentage of alumni who give to
the school.
1.15.
±orexample, blue is by far the most
popular choice; 70% of respondents chose 3
of the 10 options (blue, green, and purple).
blue
green
purple
red
black
orange
yellow
brown
gray
white
0
5
10
15
20
25
30
35
40
Percent
Favorite color