Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?

A. 60 gallons
B. 100 gallons
C. 120 gallons
D. 180 gallons

Explanation:

Work done by the waste pipe in 1 minute = 1/15 – (1/20 + 1/24) = – 1/40

Volume of 1/40 part = 3 gallons\
Volume of whole = 3 * 40 = 120 gallons.

Correct Answer: 120 gallons ✔

Last Updated: February 08, 2020