Unit Rates

Lesson 4

1. Write the ratio 12 : 18 as a fraction in simplest form2. The ratio of dogs to cats in a shelter was 4 : 3.

a) Explain the meaning of this ratio.

b) Write the ratio of dogs to total critters in the shelter.

3. Convert to a decimal.5

3

Rate: ◦ A ratio of two numbers that have different units

$ per Pound Miles per Gallon Miles per Hour

Unit Rate: ◦ A rate with a denominator of 1

pounds3

79.2$

The Denominator (bottom #) MUST be 1.

Duh how can I do that?

3

3

pound1

93.0$

Find each unit rate.

a. b.

Rewrite the rate so its denominator is 1.

hours 4

miles 80sandwiches 2

96.12$

20 miles per hour $4.32 per sandwich

An airplane flew 720 miles in 1.5 hours. How fast was it flying in miles per hour?

Write the rate as miles to hours.

Rewrite the rate so its denominator is 1.

The airplane was flying at a rate of 480 miles per hour.

hours 1.5

miles 720

A grocery store has a special on jumbo cookies. They are selling 16 jumbo cookies for $5.92. Find the price per cookie.

Write the rate as price to cookies.

Find the unit rate.

Each cookie costs $0.37.

cookies 16

92.5$

Find the unit rate.

1.

2.

3. Sue spent $3.30 for 3 ice cream cones. Dan spent $2.50 for 2 ice cream cones. Who spent less per ice cream cone?

A = Sue B = DanHint: use unit rates.

hours 4

miles 200

hats 2

44.8$

Why would you want to know the miles per gallon your car uses when it is driven? Do you think the unit rate changes if you are driving on a freeway or driving on streets? Why?