UNIT RATES
UNIT RATES

A rate is a ratio of two quantities measured in
different units. A unit rate is a rate that has a
denominator of 1 unit. The three unit rates below
are equivalent. In the third rate, “per” means “for
every.”
EXAMPLE 1 FINDING A UNIT RATE

Kudzu During peak growing season, the kudzu
vine can grow 6 inches in 12 hours. What is the
growth rate of kudzu in inches per hour?
Solution
First, write a rate comparing the inches grown
to the hours it took to grow. Then rewrite the
fraction so that the denominator is 1.

ANSWER The growth rate of kudzu is about 0.5
inch per hour.
YOUR TURN: FIND THE UNIT RATE
1.
2.
3.
1.
$54 in 6 hours
68 miles in 4 days
2 cups in 8 servings
Average Speed If you know the distance
traveled and the travel time for a moving object,
you can find the average rate, or average speed,
by dividing the distance by the time.
EXAMPLE 2 FINDING AN AVERAGE SPEED

Speed Skating A skater took 2 minutes 30
seconds to complete a 1500 meter race. What was
the skater’s average speed?
Rewrite the time so that the units are the
same.
2 min + 30 sec = 120 sec + 30 sec = 150 sec
Find the average speed.
EXAMPLE 3 COMPARING UNIT RATES

Pasta A store sells the same pasta the following
two ways: 10 pounds of bulk pasta for $15.00 and
2 pounds of packaged pasta for $3.98. To
determine which is the better buy, find the unit
price for both types.
ANSWER The bulk pasta is the better
buy because it costs less per pound.
YOUR TURN
1.
It takes you 1 minute 40 seconds to walk 550
feet. What is your average speed?
2.
Which of the following is the better buy: 2 AA
batteries for $1.50 or 6 AA batteries for $4.80?