Pumps A, B, and C operate at their respective constant rates. Pumps A and B, operating simultaneously, can fill a certain tank in 6/5 hours; pumps A and C, operating simultaneously, can fill a certain tank in 2/3 hours; and pumps B and C, operating simultaneously, can fill a certain tank in 6/5 hours. How many hours does it take A, B, and C, operating simultaneously, to fill the tank?
Is the answer 12/19 hrs?
This question wasn't difficult but very very time consuming. I wonder if this would actually appear on the real GMAT exam...?












