Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 4 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?\nOptions:\n(A) 60 gallons\n(B) 100 gallons\n(C) 120 gallons\n(D) 160 gallons\n(E) 130 gallons Let's think first. Stream of consciousness:
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Work done by the waste pipe in 1 minute = 1/15 - (1/20 + 1/24) = - 1/40\nVolume of 1/40 part = 4 gallons\\nVolume of whole = 4 * 40 = 160 gallons.
So, the answer is (D).
Assistant