Two pipes P and Q can fill a tank in 36 minutes and 45 minutes, respectively. If both pipes are opened together, the time taken to fill the tank is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 20 minutes.
Time ∝ 1/Time
Time taken by pipe P to fill the tank = 36 minutes
Pipe P fill the tank in 1 minute = 1/36
Time taken by pipe Q to fill the tank = 45 minutes
Pipe Q fill the tank in 1 minute = 1/45
Pipes P and Q together fill the tank in 1 minute = (1/36) + (1/45) = 1/20
The total time taken by two pipes = 20 minutes
Therefore, the time taken by both pipes to fill the tank is 20 minutes.