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Question
Two taps A and B can fill a tank in 16 and 32 minutes respectively. Both the taps are turned on at the same time. After how many minutes should B be turned off so that the tank can be filled in 12 minutes?
A
8 mins.
B
9 mins.
C
7 mins.
D
11 mins.
Soln.
Ans: a
Ans: a
Let B be closed after x mins. Then sum of works done by A and B = 1. $12/16 + x/32 = 1$. Solving, we get x = 8.