# Pipes A and B can fill a tank in 30 minutes and $37\frac{1}{2}$minutes, respectively. C is an outlet pipe. When all the three pipes are opened toget

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Pipes A and B can fill a tank in 30 minutes and $37\frac{1}{2}$minutes, respectively. C is an outlet pipe. When all the three pipes are opened together, then the tank is full in 25 minutes. In how much time (in minutes) can C alone empty $\frac{2}{5}th$ part of the tank?
1. 24 minutes
2. 30 minutes
3. 20 minutes
4. 25 minutes

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Correct Answer - Option 3 : 20 minutes

Given:

All pipe together can fill the tank in 25 min

Calculation:

Let us assume pipe C can empty the tank in P min

⇒ One minute's work of A, B, and C together = 1/25

⇒ 1/30 + 2/75 - 1/P = 1/25

⇒ C alone can empty the tank in P = 50 minutes

⇒ C alone can empty the 2/5th tank in = 50 × (2/5) = 20 minutes

∴ The required result will be 20 minutes.