7th Grade Math

Lesson 4B More Statistical Displays 535

Identify a Relationship

Explain whether the scatter plot

Commute Time (min)

5

0

10

0.5 12.51.5 2.0

15

Distance From School (mi)

School Commute

of the data for school commute

times shows a positive,

negative, or no relationship.

As the distance increases, the

time increases. Therefore, the

scatter plot shows a positive

relationship.

a. GRADES The graph shows

Percent^60

0

100

10 20 30

40

80

120

Student Numbers

Student Grades on Math Test

the grades on a recent math

test. Explain whether the

scatter plot shows a positive,

negative or no relationship.

The line of best fit is a line that is very close to most of the data

points in a scatter plot.

Use a Line Graph to Predict

SUMMER CAMP The graph Summer Camp Enrollment

2007 2008 2009 2010 2011 2012

60

40

20

80

100

120

140

160

180

Enrollment

200

Year

0

shows the enrollment at

a summer camp for the

past several years.

Construct a line of

best fit. If the trend

continues, what will be

the enrollment in 2014?

Draw the line that is close

to most of the data points.

If the trend continues, the

enrollment in 2014 will be

about 175 campers.

b. INTERNET The graph Web Site Hits

12345

6000

4000

2000

8000

10000

Number of Hits

Day

0

shows the number of hits

on a Web site for the first

5 days. Construct a line of

best fit. If the trend

continues, predict the day

the Web site will have

12,000 hits.

Scatter Plots Scatter Plots In a positive

relationship, as the value

of x increases, so does the

value of y. In a negative

relationship, as the value

of x increases, the value of

y decreases.

534_545_C09_L4_895130.indd 535 1/11/10 9:45 AM