7th Grade Math

Lesson 3C Statistical Displays 521

Step 3 For each time interval, draw a bar whose height is given

by its frequency.

a. SCHOOL The list at the Test Scores

94 85 73 93 75 77 89 80

89 83 79 81 87 85 90 83

88 86 83 91 93 93 92 90

91 88 96 97 98 82 90 100

right gives a set of test

scores. Choose intervals,

make a frequency table,

and construct a histogram

to represent the data.

Running Time of Movies

Number of Movies

Time (minutes)

81–

110

111–

140

141–

170

201–

230

171–

200

0

1

2

3

4

5

6

7

8

There is no space between 9

bars.

Because all of

the intervals are

equal, all of the

bars have the

same width.

Gaps Gaps Intervals with a

frequency of 0 have a

bar height of 0. This is

referred to as a gap.

Analyze and Interpret Histograms

BASEBALL How many Arizona Players’ At Bats

Number of Players

Times At Bat

0–

99

100–

199

200–

299

400–

499

300–

399

500–

599

600–

699

0

2

4

6

8

10

12

14

16

18

20

22

Arizona Diamondbacks^24

players were at bat at least

400 times in a season?

One player was at bat

400–499 times, and 3

players were at bat 500–599

times. Two players were

at bat 600–699 times.

Therefore, 1 + 3 + 2 or 6

players were at bat at least

400 times.

BASEBALL What percent of the players were at bat 199 times

or fewer?

There were 23 + 5 + 3 + 2 + 1 + 3 + 2 or 39 players at bat. There

were 23 + 5 or 28 players that were at bat 199 times or fewer.

_^28

39

≈ 0.72 Divide 28 by 39.

So, about 72% of the players were at bat 199 times or fewer.

b. What was the greatest number of times at bat for any one player?

c. Based on the data above, how many times is an Arizona

Diamondbacks player most likely to be at bat?

Percents

To write a decimal as a

percent, move the decimal

point two places to the

right and add a percent

sign.

0.67 = 67%

513_531_C09_L3_895130.indd 521 1/11/10 9:40 AM