7th Grade Math

Chapter Study Guide and Review

420 Linear Functions

Slope

Constant Rate of Change (Lesson 2B)

Find the constant rate of change for each

table.

19. Time (min) Laps Swam
    00
    12
    24
    36


20. Package Cookies
    5 60
    10 120
    15 180
    20 240


21. Yards 123 4
    Feet 36912

EXAMPLE 3 The table shows the

amount of money Hallie made doing yard

work. Find the constant rate of change in

dollars per hour.

Work

Hours Money ($)

212

424

636

848

Find the unit rate.

change in money

__change in hours = _12 dollars2 hours

= _6 dollars1 hour

So, the number of dollars earned increases

by $6 for every hour worked.

Slope (Lesson 2C)

22. CONCRETE The table shows the amount y
    of concrete that a construction company
    can pour per x minutes. Graph the data.
    Then find the slope of the line. Explain
    what the slope means.

Time (min) 15 30 45 60

Yards of Concrete 36 912

23. RAIN Yesterday, 2 inches of rain fell in 1
    hour. It kept raining at the same rate for
    several hours. Draw a graph of inches of
    rain versus time. Find the value of the
    slope and interpret it in words.

EXAMPLE 4 The graph shows the

relationship between the minutes spent

reading x and the average amount of

words read y. Find the slope of the line.

Explain what the slope represents.

slope = _riserun

= _^651

So, for every

minute of reading,

there are 65 words

read.

Lesson 2

+ 2

+ 2

+ 2

+ 12

+ 12

+ 12

Words

60

40

80

20

0

100

120

140

160

180

200

Time (min)

123

Reading

x

y

( 1 , 65 )

( 2 , 130 )

(3, 195)

418_422_C07_SGR_895130.indd 420 12/31/09 4:35 PM