Correct option is A
Given:
Pipe 1 can fill the tank in 30 minutes.
Pipe 2 can fill the tank in 60 minutes.
Pipe 3 at the bottom can empty the tank in 120 minutes.
Solution:
Work done by each pipe in 1 minute:
Work done by Pipe 1 in 1 minute =
Work done by Pipe 2 in 1 minute =
Work done by Pipe 3 in 1 minute (emptying) =
Net work done in 1 minute =
Net work done in 1 minute =
Time required to fill the tank =
Therefore, the tank will get filled in 24 minutes.