Solving a Problem

Question

Tammy, working alone, could clean one-half the area in one hour. Her partner, Melissa - working alone - could clean one-third of the area in one hour. During the contest when they work together, how long will it take them to clean the area? Explain how you found your solution.

Answer 1

Since Tammy can clean half the area in one hour, she can clean it all in 2. Two hours = 120 minutes, so she cleans 1/120 of the area each minute.

Similarly, Melissa cleans 1/180 of the area each minute.

So together, they clean 1/120 + 1/180 each minute.

1/120 + 1/180 = 3/360 + 2/360 = 5/360 = 1/72 So together it takes them 72 minutes or 1 1/5 hours..