Two pipes A and B started to fill a cuboid-shaped swimming pool. They can individually fill the tank in 60 minutes and 72 minutes. The operator of the pipe didn’t notice that the outlet pipe C was also open. Due to the outlet pipe, the pool took 40 minutes to be filled. Find the time in which the outlet pipe can empty the pool?
Two pipes A and B started to fill a cuboid-shaped swimming pool. They can individually fill the tank in 60 minutes and 72 minutes. The operator of the pipe didn’t notice that the outlet pipe C was also open. Due to the outlet pipe, the pool took 40 minutes to be filled. Find the time in which the outlet pipe can empty the pool? Correct Answer 3 hrs
Given:
Time taken by Pipe A to fill the pool = 60 minutes
Time taken by pipe B to fill the pool = 72 minutes
Time taken by Pipe (A, B, C) together to fill the pool = 40 minutes
Formula used:
1 minute’s work = 1/(Total time taken to complete the work)
Calculation:
Work done by A in 1 min = 1/60
Work done by B in 1 min = 1/72
Work done by A, B, C in 1 min = 1/40
⇒ (A + B + C)’s 1 min work = A’s 1 min work + B’s 1 min work + C’s 1 min
⇒ 1/40 = 1/60 + 1/72 – 1/C
⇒ 1/c = 1/60 + 1/72 – 1/40
⇒ 1/C = (6 + 5 – 9)/360
⇒ 1/C = 2/360
⇒ C = 180 minutes
∴ Time taken by C to empty the tank = 180 minutes = 3 hrs