Two pipes X and Y can fill a cistern in 24 minutes and 32 minutes respectively. If both the pipes are opened together, then after how much time should pipe Y be closed so that the tank is full in 18 minutes?
A
6 minutes
B
8 minutes
C
10 minutes
D
12 minutes
Correct Option:
B
Explanation
Pipe X fills 18/24 = 3/4 of the cistern in 18 minutes. The remaining 1/4 must be filled by pipe Y. Since Y fills the whole cistern in 32 minutes, it fills 1/4 in 8 minutes. Therefore, pipe Y should be closed after 8 minutes.
