7th Grade Math

522 Statistical Displays

Example 1 1. POPULATION The list U.S. State Population Density (per square mile)

88 42 189 33 810 6 15 50 10 179

1 703 16 102 175 22 402 36 138 89

45 401 223 103 62 18 165 274 80 75

51 296 170 41 61 138 9 1,003 27 99

217 141 52 542 81 1,135 277 133 66 5

gives the approximate

population density for

each state. Choose

intervals and make a

frequency table. Then

construct a histogram

to represent the data.

Examples 2 and 3 2. VOLCANOES Use the histogram North American Active Volcanoes

Number of Volcanoes

Height (feet)

3,000–5,9996,000–8,9999,000–11,99912,000–14,99915,000–17,99918,000–20,999

0

2

4

6

8

10

at the right.^12

a. What percent of the

volcanoes are 8,999 feet

or less?

b. How likely is it that any

given volcano is at least

15,000 feet tall? Explain

your reasoning.

c. What is the height of the

tallest volcano?

= Step-by-Step Solutions begin on page R1.

Extra Practice begins on page EP2.

For each problem, choose intervals and make a frequency table. Then

construct a histogram to represent the data.

Example 1

3. Hours Spent Exercising per Week
   3091420
   36144253
   7308310
   4. Average Speed (mph), Selected Animals
   70 61 50 50 50 45 8
   43 42 40 40 40 35 0.17
   35 32 32 30 30 30 1.17
   30 25 20 9 18 14 200

Examples 2 and 3 55 COUNTRIES Use the histogram below.

a. How many countries have Area of the Smallest Countries

Number of Countries

Area (square kilometers)

1–

200

201–

400

401–

600

801–

1,000

601–

800

1,001–

1,200

0

2

4

6

8

10

12

14

16

18

20

22

an area less than 401 square^24

kilometers?

b. What percent of the countries

have an area of 201–600

square kilometers?

c. How likely is it that any

given country will have an

area greater than 800 square

kilometers? Explain.

513_531_C09_L3_895130.indd 522 1/11/10 9:40 AM