Question

If $\frac{4}{5}$ of a water tank is filled in $1$ hour, how much time will be required to fill the rest of it?

• A. $20$ minutes
• B. $15$ minutes
• C. $12$ minutes
• D. $10$ minutes

Answer 1

The correct option is B $15$ minutes

Given $\frac{4}{5}$ of a water tank is filled in $1$ hr i.e. $60$ mins.

The rest of the tank i.e. $1-\frac{4}{5}=\frac{1}{5}$ of the tank will be filled in

$\frac{60}{\frac{4}{5}}\times \frac{1}{5}=\frac{60}{4}=15$ mins.