Question

Al can wash a car in 60 minutes, and bill can wash a car in 30 minutes. cathy can wash a car in 20 minutes. how long, in minutes, would it take the 3 of them to wash a car, working together?
a. 10

b. 36

c.

d. 110

Answer 1

B) 36

To figure this out you need to average the numbers. To average them you add them all up and divide by how many are there.
(60+30+20)/3
(90+20)/3
110/3
36