Course 3

5-2 Ratios, Rates, and Unit Rates5-2 Rates, and Unit Rates

Course 3

Warm Up

Problem of the Day

Lesson Presentation

Course 3

5-2 Ratios, Rates, and Unit Rates

Vocabulary

rateunit rateunit price

Course 3

5-2 Ratios, Rates, and Unit Rates

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.

Course 3

5-2 Ratios, Rates, and Unit Rates

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

Course 3

5-2 Ratios, Rates, and Unit Rates

Additional Example 1: Finding Unit Rates

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

Write a rate.

=

Fred 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

Course 3

5-2 Ratios, Rates, and Unit Rates

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

Course 3

5-2 Ratios, Rates, and Unit Rates

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

Course 3

5-2 Ratios, Rates, and Unit Rates

Pens can be purchased in a 5-pack for $1.95 or a 15-pack for $6.20. Which is the better buy?

Additional Example 4A: Finding Unit Prices to Compare Costs

Divide the price by the number of pens.

price for packagenumber of pens

$1.955

= $0.39

price for packagenumber of pens

= $6.2015

$0.41

The better buy is the 5-pack for $1.95.

Course 3

5-2 Ratios, Rates, and Unit Rates

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 4B: 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.

Course 3

5-2 Ratios, Rates, and Unit Rates

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 4A

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.

Course 3

5-2 Ratios, Rates, and Unit Rates

Check It Out: Example 4B

John can buy a 24 oz bottle of ketchup for $2.19 or a 36 oz bottle for $3.79. Which is the better buy?

$2.1924

= $0.09

= $3.7936

$0.11

The better buy is the 24-oz jar for $2.19.

price for bottlenumber of ounces

price for bottlesnumber of ounces

Divide the price by the number of ounces.

Course 3

5-2 Ratios, Rates, and Unit Rates

5. Bob typed 593 words in 4 minutes. How many words did Bob type per minute?

1. Jacob can buy a 32 oz bottle of BBQ sauce for $2.93 or a 36 oz bottle for $3.19. Which is the better buy?

2. John can buy a 8 pencils for $1.25 or a 12 pencils for $2.00. Which is the better buy?

3. Mary made $25.00 for working 7 hours at the mall. How much did Mary make per hour?

4. Lisa paid $158.00 for 3 pair of jeans. What did Lisa pay for each pair of jeans?

Try These!

Course 3

5-2 Ratios, Rates, and Unit Rates

5. 593 / 4 minutes = 148.3 words/minute

1. $2.93 / 32 = $0.09 (better buy) $3.19 / 36 = $11.6

2. $1.25 / 8 = $0.16 (better buy) $2.00 / 12 = $0.17

3. $25.00 / 7 hours = $3.57 / Hr

4. $158.00 / 3 pair of jeans = $52.67 / jean

Try These! Round to nearest hundredth