Unit Rates

A rate is a ratio that compares quantities in different units. Rates are commonly found in everyday life. The prices in grocery stores and department stores are rates. Rates are also used in pricing gasoline, tickets to a movie or sporting event, in paying hourly wages and monthly fees.

A unit rate is a rate where the second quantity is one unit, such as $34 per pound, 25 miles per hour, 15 Indian Rupees per Brazilian Real, etc.

Example 1:

A motorcycle travels 230 miles on 4 gallons of gasoline. Find the average mileage per gallon.

For this problem, simply divide 230 by 4.

The motorcycle gets 57.5 miles per gallon.

Example 2:

A copy machine makes 45 copies in 25 second. Find the unit rate of copies per second.

Divide 45 by 25 to find the unit rate.

The copy machine makes 1.8 copies per second.