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40 UNIT 1 Exploring One-Variable Data

(b) Statistics instructor Paul Myers collected data on the Comparing Distributions of Quantitative Data

ages (in years) of family members for each student in 13. Calcium in yogurt Which dairy yogurt is healthier:
his class. The dotplot displays the data. Describe the pg 28 plain or flavored? The Nutrition Action Healthletter
shape of the distribution. provided data on calories, saturated fat, protein, calcium,
and total sugars for many popular brands of yogurt. 43
Here are parallel dotplots that display the data on cal-
plain and flavored dairy yogurt. Compare the distribu-Copy
cium content as a percentage of the recommended daily
value (%DV) of 1000 milligrams for several brands of
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tions of calcium content in these two types of yogurt.

Flavored

Type
0 10 20 30 40 50 60 70 80
Age (years)

Describing Distributions of Quantitative Data Plain
9. Feeling sleepy? A statistics professor asked how 0 5 10 15 20 25 30 35 40
pg 26 much sleep (in hours) students got on the night prior to Calcium (%DV)
their first exam. Here is a dotplot of the data from the
50 students in the class. Describe the distribution. 14. Healthy streams Nitrates are organic compounds that
are a main ingredient in fertilizers. When fertilizers
run off into streams, the nitrates can have a toxic effect
on fish. An ecologist studying nitrate pollution in two
streams measures nitrate concentrations at 42 places in
Stony Brook and 42 places in Mill Brook. The parallel
dotplots display the data. Compare the distributions of
nitrate concentration in these two streams.

0 1 2 3 4 5 6 7 8 9
Amount of sleep (h)
Stony Brook
10. Frozen pizza Consumer Reports collected data on the
number of calories per serving for 16 brands of frozen Mill Brook
cheese pizza as part of its product reviews. Here is a 0 2 4 6 8 10 12 14 16 18 20
42

dotplot of the data. Describe the distribution. Nitrate concentration (mg/l)
15. Enhancing creativity Do external rewards — like
money, praise, fame, and grades — promote creativity?
260 270 280 290 300 310 320 330 340 350 360 370 380 Researcher Teresa Amabile recruited 47 experienced
Calories
creative writers who were college students and divided
11. Soccer distribution Refer to Exercise 3. them at random into two groups. The students in one
group were given a list of statements about external rea-
(a) Describe the shape of the distribution. Are there any

outliers? sons (E) for writing, such as public recognition, making

(b) How many goals did the team score in a typical game money, or pleasing their parents. Students in the other
group were given a list of statements about internal
that season? Explain your answer. reasons (I) for writing, such as expressing yourself and
12. Fuel distribution Refer to Exercise 4. enjoying playing with words. Both groups were then

(a) Describe the shape of the distribution. Are there any instructed to write a poem about laughter. Each stu-
outliers? dent’s poem was rated separately by 12 different poets
44
(b) What is the typical fuel efficiency of the 21 cars in the using a creativity scale. These ratings were averaged

sample? Explain your answer. to obtain an overall creativity score for each poem.

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