A leak empties $\frac1{20}$ of a tank in one hour, while a tap fills $\frac1{5}$ of the tank in one hour. The fraction filled in one hour when both operate is:

Question

A leak empties $\frac1{20}$ of a tank in one hour, while a tap fills $\frac1{5}$ of the tank in one hour. The fraction filled in one hour when both operate is:

Option A

$\frac1{4}$

Option B — Correct answer

$\frac3{20}$

Correct choice.

Option C

$\frac1{5}$

Option D

$\frac7{20}$

Explanation

Net rate $=\frac15-\frac1{20}=\frac4{20}-\frac1{20}=\frac3{20}$.

Chapter Mock 7: Time and Work, Pipe and Cistern