Question

Egan needs to drain his 21,000​-gallon inground swimming pool to have it resurfaced. He uses two pumps to drain the pool. One drains 15 gallons of water a minute while the other drains 20 gallons of water a minute. If the pumps are turned on at the same time and remain on until the pool is​ drained, how long will it take for the pool to be​ drained?

Answer 1

600 minutes

Explanation:

The total rate of the Pump is gotten first

15 + 20 = total rates of 35 gallon per hour .

rate = volume/ time.

Volume = rate * time

21,000 = 35 * t

t = 21,000/35

t = 600 minutes.

To check the volume each pump will pump out.

pump A 15 * 100 = 9000 gallons

Pump B 20 * 600 = 12000 gallons.

12,000+9,000= 21,000 which gives the total gallons of the swimming pool back