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0.35
Relative frequency 0.40 Setosa
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0.25
0.20
0.15
0.10
0.05
44 UNIT 1 Exploring One-Variable Data 0.00
4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
Sepal length (cm)
(b) Describe the shape of the distribution. Are there any Versicolor
outliers? 0.40
(c) Estimate the center and variability of the distribution. 0.35
31. Value of a college degree Is it true that students who 0.30
earn an associate’s degree or a bachelor’s degree make 0.25
more money than students who attend college but do Relative frequency 0.20
not earn a degree? To find out, we selected a random
sample of 500 U.S. residents aged 18 and older who 0.15
had attended college from a recent Current Popula- 0.10
54
tion Survey. The educational attainment and annual 0.05
income of each person were recorded. Here are relative 0.00
frequency histograms of the income data for the 327 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
college graduates and the 173 nongraduates: Sepal length (cm)
Virginia
College graduates
Relative frequency (%) 40 Relative frequency 0.30
0.35
50
30
0.25
20
0.20
10
0
20
0
80 100 120 140 160 180 200 220 240 260 280 300 320 340
40 60
0.10
Annual income ($1000s) 0.15
0.05
Nongraduates 0.00 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
Relative frequency (%) 40 0.352024 BFW Publishers PAGES NOT FINAL - For Review Purposes Only - Do Not Copy
60
50
Sepal length (cm)
30
(a) Compare the distributions of sepal length for the three
20
species.
10
0
40 60
0
20
80 100 120 140 160 180 200 220 240 260 280 300 320 340
instead of relative frequency histograms in this setting?
Annual income ($1000s) (b) Would it be appropriate to use frequency histograms
Explain why or why not.
(a) Compare the distributions of annual income for the
two groups. 33. Body mass index Researchers wanted to investigate
(b) Would it be appropriate to use frequency histograms the relationship between blood pressure and body mass
instead of relative frequency histograms in this setting? index (BMI) in predominantly lean African popula-
Explain why or why not. tions. As part of the research, they collected data on
32. Irises U.S. botanist Edgar Anderson collected data on 50 BMI from a sample of 338 rural and 290 semi-urban
women in Ghana. Here are comparative histograms of
iris flowers from each of three different species: Setosa, the data for the two groups: 56
55
Versicolor, and Virginia. British statistician Ronald
Fisher used these data to develop a way of classifying an Semi-urban Rural
individual iris based on measurements (in centimeters) of
sepal length, sepal width, petal length, and petal width. 25
Here are histograms of the data on sepal length:
20
Setosa
0.40 Percent 15
© 0.30 10
Relative frequency 0.25 5 0 12 16 20 24 28 32 36 40 12 16 20 24 28 32 36 40
0.20
0.15
0.10
2
2
0.05 BMI (kg/m ) BMI (kg/m )
0.00 (a) Describe similarities and differences between the two
4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 distributions.
Sepal length (cm)
Versicolor
0.40
© 2024 BFW Publishers PAGES NOT FINAL - For Review Purposes Only, all other uses prohibited - Do Not Copy or Post in Any Form.
0.35
Relative frequency 0.20
0.30
02_StarnesTPS7e_40934_un01_p1_001_086_6pp.indd 44 13/09/23 5:38 PM
0.25
0.15
0.10
0.05
0.00
4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
Sepal length (cm)
Virginia

0.35
Relative frequency 0.25
0.30
0.20
0.15
0.10
0.05
0.00
4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
Sepal length (cm)