Page 380 - Basic College Mathematics with Early Integers

S E C T ION 5 .1 I RATIOS 357

16 gallons
Concept Check True or false? is a rate. Explain.
4 gallons

Objective Finding Unit Rates
A unit rate is a rate with a denominator of 1. A familiar example of a unit rate is
55 mph, read as “55 miles per hour.”This means 55 miles per 1 hour or
55 miles
Denominator of 1
1 hour
In this context,
the word “per” translates to
division.

Writing a Rate as a Unit Rate

To write a rate as a unit rate, divide the numerator of the rate by the denominator.

Example 9 Write as a unit rate: $31,500 every 7 months PRACTICE 9
Write as a unit rate: 3200 feet
Solution: every 8 seconds

31,500 dollars 4,500
7 months 731,500

The unit rate is

4500 dollars
or 4500 dollars/month Read as,“4500 dollars per month.”
1 month
Work Practice 9

Example 10 Write as a unit rate: 337.5 miles every 15 gallons of gas PRACTICE 10
Write as a unit rate: 78 bushels
Solution: of fruit from 12 trees

337.5 miles 22.5
15 gallons 15337.5

The unit rate is

22.5 miles
or 22.5 miles/gallon Read as,“22.5 miles per gallon.”
1 gallon
Work Practice 10

Objective Finding Unit Prices
Answers
Rates are used extensively in sports, business, medicine, and science. One of the 400 ft
9. or 400 ft/sec
most common uses of rates is in consumer economics. When a unit rate is “money 1 sec
per item,” it is also called a unit price. 6.5 bushels
10. or 6.5 bushels/tree
1 tree
price
unit price =
number of units Concept Check Answer
false; a rate compares different
kinds of quantities