If 12 people can wah 40 cars in 12 days.How many days will it take for 4 people to wash 30 cars?

Answer 1

This is a rate problem where you can use R = (N/t)/n, where N is the number of cars, t is the time and n is the number of folks. Plugging in the info from the first set of numbers you will obtain a rate of 5/18 which means that one person can wash a little less than half a car per day.

Set this rate equal to same formula, but now substitute the data from the second set. This will leave you with one equation and one unknown, e.g., t. Solving this equation you will get 27 for the answer.

Answer 2

144 person/days to do 40 cars

108 person/days to do 30 cars (30 is 3/4 of 40)

4 people would need 27 days (108 = 4 times 27)