Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 5 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?
Options:
(A) 60 gallons
(B) 200 gallons
(C) 120 gallons
(D) 180 gallons
(E) 130 gallons Think first, then make a decision. Some random thoughts:
user
Work done by the waste pipe in 1 minute = 1/15 - (1/20 + 1/24) = - 1/40
Volume of 1/40 part = 5 gallons\
Volume of whole = 5 * 40 = 200 gallons. So the answer is (B).
assistant