Two pumps are connected to an empty tank. Pump X fills the tank with water at a constant rate, while pump Y drains water out of the tank at a constant rate. The two pumps finish filling the tank in six times the duration it would take pump X alone to fill the tank. If pump Y alone can empty a whole tank in 48 minutes, then how many minutes does it take pump X alone to fill the tank?
Pick one:
A) 32  B) 34  C) 36  D) 38  E) 40
Let V be the volume of the tank.   Let R be the rate per minute that pump X fills the tank.   Let T be the time it takes pump X to fill the tank.   The rate at which pump Y empties the tank is V/48 per minute.   (R - V/48)*6T=V=RT.   (R-V/48)*6=R   5R=V/8.   R=V/40.   It takes pump X 40 minutes to fill the tank.   The answer is 40.
<result>E</result>
Two pumps are connected to an empty tank. Pump X fills the tank with water at a constant rate, while pump Y drains water out of the tank at a constant rate. The two pumps finish filling the tank in six times the duration it would take pump X alone to fill the tank. If pump Y alone can empty a whole tank in 48 minutes, then how many minutes does it take pump X alone to fill the tank?