7th Grade Math

414 Linear Functions

Example 1 11 MUSIC The table shows the Length (in.) 48 36 24 12

Frequency

(cycles/s)^3604807201440

relationship between the length

of a piano string and the frequency

of its vibrations. Graph the data in

the table and determine if the relationship is an inverse variation.

Example 2 2. TRAVEL The time it takes to travel a certain distance varies inversely with

the speed at which you are traveling. Suppose it takes 3 hours to drive

from one city to another at a rate of 65 miles per hour. How long will the

return trip take traveling at 55 miles per hour?

= Step-by-Step Solutions begin on page 614.

Extra Practice begins on page 520.

Graph the data in each table and determine if the relationship is an

inverse variation.

3. 
   

   (^) Length (m) 2.4 3 6 10
   Width (m) 15 12 6 3.6

   
   


4. 
   

   (^) Gift Card
   Balance ($) 50.00 42.50 27.50 5.00
   Number
   of Movies^0136
   Example 2 5. BRICKS The number of bricklayers needed to build a brick wall varies
   inversely as the number of hours needed. Four bricklayers can build a brick
   wall in 30 hours. How long would it take 5 bricklayers to build a wall?

   
   


5. 
   

   RUNNING In the formula d = rt, the time t varies inversely with the rate r.
   A student running at 5 miles per hour runs one lap around the school
   campus in 8 minutes. If a second student takes 10 minutes to run one lap
   around the school campus, how fast is she running?
   77 GRAPHIC NOVEL Refer to the graphic novel frame below. Seth applies
   his brakes and begins slowing. Suppose the car travels 88 feet after
   2 seconds. After 4 seconds the car travels another 44 feet. It takes several
   more seconds for the car to come to a complete stop. Is this an example
   of direct or inverse variation? Explain.

   
   

B

Example 1

Slowing down

after racing is

mathematical

too.

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