Unit Rate Review

From Ratios to Rates

Essential Question:How are ratio, rate and unit rate

related to each other?

Introduction to Rates & Unit Rates

Pepsi was on sale last week: It cost $10 for every 4 packs of Pepsi.

How much do 2 packs of Pepsi cost?

2 packs of Pepsi cost $5.00

Packs of Pepsi 4 2

Total Cost 10 5

Introduction to Rates & Unit Rates

Pepsi was on sale last week: It cost $10 for every 4 packs of Pepsi.

How much does 1 pack of Pepsi cost?

1 pack of Pepsi cost $2.50

Packs of Pepsi 2 1

Total Cost 5 2.50

Rate and Unit Rate Terminology

• Rate - $10 for every 4 packs of Pepsi is a rate

• Unit Rate – The unit rate is 2.5 because it is the value of the ratio

• Rate Unit (Label) – The rate unit is dollars/packs of Pepsi because it costs 2.5 dollars for every 1 pack of Pepsi

Ratio – Unit Rate – Rate Model

Key Vocabulary• A ratio is a comparison of two quantities by division.

� 17 out of 20 students, or

• A rate is a special type of ratio comparing two quantities with different units.– Driving 120 miles in 2 hours, or

• A unit rate is a rate that is simplified so that it has a denominator of 1 unit. – Driving 120 miles in 2 hours, or

20

17

hours 2

miles 120

hour 1

miles 60

hours 2

miles 120

Example 1:Andy biked 24 miles in 4 hours. If he

traveled at a constant speed, how many miles did he ride in 1 hour?

hours

miles

hours 4

miles 24

Write a verbal model of what you are comparing.

Substitute in the values given for each quantity.

hour 1

miles 6

4 4

4 24

Since a unit rate has a

denominator of 1 unit, divide the numerator and denominator by 4.

Andy biked 6 miles per hour.

Example 2:A 12-pack of Gatorade costs $13.44.

What is the unit price per bottle?

bottle

cost

bottles 12

$13.44

Write a verbal model of what you are comparing.

Substitute in the values given for each quantity.

Divide the numerator and denominator by 12 to find the unit rate.

The unit price is $1.12 per bottle.

bottle 1

$1.12

1212

1244.13$

Example 3:The price of three different bags of

cat food are shown in the table to the right. Which bag has the lowest price per pound?

pound

priceWrite a verbal model of what you are comparing.

lb 1

$1.38

3.5 3.5

3.5 $4.83

For the 3.5 lb bag,

The 7 pound bag is the least expensive at $1.35 per pound

Cat Food PricesSize of bag

(lbs)Price

($)3.5 4.837 9.45

20 27.20

lb 1

$1.35

7 7

7 $9.45

For the 7 lb bag,

lb 1

$1.36

20 20

20 $27.20

For the 20 lb bag,

Example 4:After 3.5 hours, Peyton had traveled 161miles. If she travels at

a constant speed, how far will she have traveled in 4 hours?

hours

miles

hour 1

miles 46

3.5 hours 3.5

3.5 miles 161

Write a verbal model of what you are comparing.

Find the unit rate in miles per hour.

Multiply the unit rate, or average speed, by the number of hours traveled.

Peyton travels 184 miles in 4 hours.

miles 184hours) 4(hour 1

miles 46

Example 5:Jerry can jog 1⅓ miles in ¼ hour. Find

his average speed in miles per hour.

hour

miles

hour 41

miles 31

1

Write a verbal model of what you are comparing.

Substitute in the values given for each quantity.

hour 1

miles 31

5

hour 1

miles 14

34

41

41

41

31

1

Since average speed in miles per 1 hour, divide the numerator and denominator by ¼ .

Jerry jogs at an average speed of 5 ⅓ miles per hour.

Example 6:Mr. Isaacs is spreading mulch in his yard.

He spreads 4⅔ square yards in 2 hours. How many square yards can he mulch in 1 hour?

hours

yds. sq.

hours 2

miles 32

4

Write a verbal model of what you are comparing.

Substitute in the values given for each quantity.

hour 1

sq.yds. 31

2

hour 1

yds. sq. 21

3

14

2 212

32

4

Divide the numerator and denominator by 2 to find the unit rate.

Mr. Isaacs can mulch 2 ⅓ square yards per hour.