7th Grade Math

398 Linear Functions

Example 1 11 SNACKS The table below shows the number of small packs of fruit

snacks y per box x. Graph the data. Then find the slope of the line.

Explain what the slope represents.

Boxes, x 3579

Packs, y 24 40 56 72

Example 2 2. TEMPERATURE At 2:00 p.m., the temperature is 81°F. At 3:00 p.m., the

temperature is 78°F. Draw a graph of temperature versus time if the

temperature continues to decrease at this rate from 2:00 p.m. to 6:00 p.m.

Find the value of the slope and interpret it in words.

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

Extra Practice begins on page EP2.

Example 1 3. CYCLING The table shows the distance y Adriano traveled in x minutes

while competing in the cycling portion of a triathlon. Graph the data.

Then find the slope of the line. Explain what the slope represents.

Time (min) 45 90 135 180

Distance (km) 51015 20

4. MARKERS The table below shows the number of markers per box.
   Graph the data. Then find the slope of the line. Explain what the slope
   represents.

Boxes 1234

Markers 8 162432

Example 2 5. MEASUREMENT There are 3 feet for every yard. Draw a graph of feet

versus yards. Find the numerical value of the slope and interpret it in

words.

6. SWIMMING Joshua swims 25 meters in 1 minute. Draw a graph of meters
   swam versus time. Find the value of the slope and interpret it in words.

B 77 SPEED The graph shows the average speed Average Speed

Distance (mi)

64

32

96

128

160

192

224

256

288

0 1234 56

Time (h)

x

y

(1.5, 67.5)

(2, 90)

(1.5, 90)

Car ACar B

(2, 120)

of two cars on the highway.

a. What does (2, 120) represent?

b. What does (1.5, 67.5) represent?

c. What does the ratio of the y-coordinate

to the x-coordinate for each pair of

points on the graph represent?

d. What does the slope of each line

represent?

e. Which car is traveling faster? How

can you tell from the graph?

391_400_C07_L2_895130.indd 398 12/31/09 4:26 PM