Question

A tap can empty a tank in one hour. A second tap can empty it in $30$ minutes. If both the taps operate simultaneously, how much time is needed to empty the tank?

Answer 1

$1$ hour $=60$ minutes

Rate of emptying the tank by the two taps are $\frac{1}{60}$ and $\frac{1}{30}$ of the tank per minute respectively.

Rate of emptying the tank when both operate simultaneously

$=\frac{1}{60}+\frac{1}{30}=\frac{1+2}{60}=\frac{3}{60}=\frac{1}{20}$

of the tank per minute.

$\therefore$ Time taken by the two taps together to empty the tank $=20$ minutes.