Proportions and Unit Rate

Unit Rate

100

410 miles in 16 gallons

What is 25.63 miles/gallon

200

1500 words in 25 minutes

What is 60 words per minute

300

$1.12 for 8.2 ounces

What is $.14 per ounce

400

Which is the better buy? $3.29 for a 16-ounce bag of candy $2.99 for a 12-ounce bag of candy

What is $3.99 for 16-ounce bag = $0.21 per ounce

500

Ethan can buy 4 CDs for $71.96 at CD Express or 9 CDs for $134.55 at Music Rox. Which has the better unit cost? How much is he saving per CD?.

What is Music Rox has the better buy (14.95 per CD). Ethan saved $3.04 per CD

Proportions

100

Do each pair of ratios form a proportion? 2/3 and 6/9

What is Yes. (18 = 18)

200

Do the ratios form proportions? 5/4 and 25/16

What is No (80;100)

300

Do the ratios form proportions? $8/20 lbs and $24/60 lbs

What is Yes (480 = 480)

400

Do the ratios form proportions? 5 ft/7 s and 25 ft/ 49 s

What is No

500

Do the ratios form proportions? 21 mi/6 h and 14.3 mi/ 3 hr

What is No

Solving Proportions

100

n/12 = 6/18

What is n = 4

200

c/28 = 5/7

What is c = 20

300

2/x = 7/9

What is x = 2.57

400

30/14 = k/1.54

What is k = 3.3

500

380/520 = 760/x

What is x = 1040

Constant of Proportionality

100

x  y

3  9

5  15

6  18

K = 3

200

x  y

2  16

3  24

5  40

k = 8

300

x  y

4  24

6  ?

8  48

What is the missing value in the table.

36

400

x  y

9  18

25  50

19  38

Write the constant of Proportionality as an equation

y = 2x

500

x  y

4   2

8   4

20  10

k = 1/2