1. U NIT R ATES

2. 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.”

3. E XAMPLE 1 F INDING A U NIT R ATE 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.

4. Y OUR TURN : F IND THE UNIT RATE 1. $54 in 6 hours 2. 68 miles in 4 days 3. 2 cups in 8 servings 1. 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.

5. E XAMPLE 2 F INDING AN A VERAGE S PEED 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.

6. E XAMPLE 3 C OMPARING U NIT R ATES 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.

7. Y OUR T URN 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?