Question

Two water pumps, working simultaneously at their respective constant rates, took exactly four hours to fill a certain swimming pool. If the constant rate of one pump was 1.5 times the constant rate of the other, how many hours would it have taken the faster pump to fill the pool if it had worked alone at it's constant rate?

A. 5
B. 16/3
C. 11/2
D. 6
E. 20/3

Answer 1

E. 20/3.

Explanation:

Working in rates per hour to fill the pool:

1 / 1.5t + 1 / t = 1/4 where t = time in hours.

Multiplying through by 12t:

8 + 12 = 3t

t = 20/3 hours.

Answer 2

A.5

Explanation: