Two pipes A and B can fill a tank in 15 hours and 18 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: D
Explanation
The correct answer is option 4 i.e. 8
Pipe A can fill in 15 hours.
Pipe B can fill in 18 hours.
Tank filled by Pipe A in 1 hour = 1/15
Tank filled by Pipe B in 1 hour = 1/18
Tank filled by both Pipes in 1 hour = (1/15) + (1/18) = 11/90
Time taken By both pipes to fill the tank = 90/11 = 8 2/11 hours