Ratios, Rates, and Unit Rates5-2

Warm UpDivide. Round answers to the nearest tenth.

1. 2.

3. 4.

23.3 3.5

23.8 23.9

420 18

73 21

380 16

430 18

Ratios, Rates, and Unit Rates5-2

Learn to work with rates and ratios.

Ratios, Rates, and Unit Rates5-2

Ratio: 903

Rate: 90 miles3 hours

Read as “90 miles per 3 hours.”

A rate is a comparison of two quantities that have different units.

Ratios, Rates, and Unit Rates5-2

Unit rates are rates in which the second quantity is 1.

unit rate: 30 miles,1 hour

or 30 mi/h

The ratio 903

can be simplified by dividing:

903

= 301

Ratios, Rates, and Unit Rates5-2

Additional Example 1: Finding Unit Rates

Geoff can type 30 words in half a minute. How many words can he type in 1 minute?

Write a rate.

=

Geoff can type 60 words in one minute.

Multiply to find words per minute.

60 words 1 minute

30 words minute

12

30 words • 2 minute • 212

Ratios, Rates, and Unit Rates5-2

Check It Out: Example 1

Penelope can type 90 words in 2 minutes. How many words can she type in 1 minute?

90 words 2 minutes

Write a rate.

=

Penelope can type 45 words in one minute.

90 words ÷ 2 2 minutes ÷ 2

Divide to find words per minute.

45 words 1 minute

Ratios, Rates, and Unit Rates5-2

Unit price is a unit rate used to compare price per item.

Ratios, Rates, and Unit Rates5-2

Jamie can buy a 15-oz jar of peanut butter for $2.19 or a 20-oz jar for $2.78. Which is the better buy?

Additional Example 4: Finding Unit Prices to Compare Costs

$2.1915

= $0.15

= $2.7820

$0.14

The better buy is the 20-oz jar for $2.78.

price for jarnumber of ounces

price for jarnumber of ounces

Divide the price by the number of ounces.

Ratios, Rates, and Unit Rates5-2

Golf balls can be purchased in a 3-pack for $4.95 or a 12-pack for $18.95. Which is the better buy?

Check It Out: Example 4

Divide the price by the number of balls.

price for packagenumber of balls

$4.953

= $1.65

price for packagenumber of balls

= $18.9512

$1.58

The better buy is the 12-pack for $18.95.

Ratios, Rates, and Unit Rates5-2

Standard Lesson Quiz

Lesson Quizzes

Lesson Quiz for Student Response Systems

Ratios, Rates, and Unit Rates5-2

Lesson Quiz: Part I

1. Meka can make 6 bracelets per half hour. How many bracelets can she make in 1 hour?

2. A penny has a mass of 2.5 g and a volume of

approximately 0.360 cm3. What is the

approximate density of a penny?

3. Melissa is driving to her grandmother's house.

In the first 3 hours of the drive, she travels 159

miles. What is Melissa's average speed?

≈ 6.94 g/cm3

53 mi/h

12

Ratios, Rates, and Unit Rates5-2

Lesson Quiz: Part II

Determine the better buy.

5. A half dozen carnations for $4.75 or a dozen for

$9.24 a dozen

Ratios, Rates, and Unit Rates5-2

1. John can walk 16 miles in 4 hours. How many

miles can he walk in one hour?

A. 16 miles

B. 8 miles

C. 4 miles

D. 2 miles

Lesson Quiz for Student Response Systems

Ratios, Rates, and Unit Rates5-2

2. Estimate the unit rate.

272 sailors in 17 ships

A. 12 sailors per ship

B. 14 sailors per ship

C. 16 sailors per ship

D. 18 sailors per ship

Lesson Quiz for Student Response Systems

Ratios, Rates, and Unit Rates5-2

3. Which of the following would be a better buy than purchasing 4 mangoes for $16?

A. 2 mangoes for $10

B. half a dozen mangoes for $25

C. 8 mangoes for $ 28

D. one dozen mangoes for $54

Lesson Quiz for Student Response Systems