Two pipes X and Y can fill a tank in 14 hours and 21 hours, respectively. Both pipes are opened simultaneously to fill the tank. In how many hours will the empty tank be filled?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. hours.
Two pipes X and Y can fill a tank in 14 hours and 21 hours, respectively
L.C.M(14, and 21) = 42
The efficieny of pipe X = 42/14 = 3 units
The efficieny of pipe Y = 42/21 = 2 units
So,
Time taken by both pipes = 42/(3 + 2) = 42/5 = hours