7th Grade Math

EP20 Extra Practice

Extra Practice

Multi-Part Lesson 7-3: Variation

PART A PAGES 402–403

CLUBS Use the table that shows the math Math Club Membership

Year Number ofStudents

2007 20

2008 21

2009 30

2010 34

2011 38

2012 45

club membership from 2007 to 2012.

1. Make a graph of the data.


2. Describe how the number of math club
   memberships changed from 2007 to 2012.


3. What is a reasonable prediction for the
   membership in 2013 if this membership
   trend continues?

PARTS B C PAGES 404–410

TRAVEL Use the graph that shows distance traveled. Total Distance Traveled per Hour

100

150

50

0

200

250

300

350

400

Distance (mi)

450

Time (h)

1234567

1. The number of miles traveled varies directly
   with the number of hours traveled. What is
   the rate of speed in miles per hour?


2. Going at the rate shown, what distance
   would one travel in 39 hours?


3. GAS MILEAGE Dustin’s car can travel about
   100 miles on 3 gallons of gas. Assuming
   that the distance traveled remains
   constant to the amount of gas used, how
   many gallons of gas would be needed to
   travel 650 miles?


4. MONEY Determine whether the linear function shown is a direct
   variation. If so, state the constant of variation.

Years, x^2345

Savings, y $2,154 $3,231 $4,308 $5,385

PARTS D E PAGES 411–415

1. PROGRAMS The cost to print programs for football season varies
   inversely as the number of programs printed. If 1,250 programs are
   printed, the cost is $2.00 each. Find the cost per program if 2,000 programs
   are printed.


2. GEOMETRY The base b of a parallelogram varies inversely as the height h.
   If the base is 9.3 meters when the height is 1.4 meters, what is the base of
   a parallelogram when the height is 3.2 meters?


3. COOKIES The number of bakers needed to make 100 cookies varies
   inversely as the number of hours needed. Three bakers can make the
   cookies in 120 minutes. How long will it take 4 bakers to make the
   cookies? Assume that they all work at the same rate.

EP2_EP36_ExtPract_M1_895130.indd EP20 1/6/10 11:46 AM