Question

A small village, having a population of 5,000 requires 75 litres of water per head per day. The village has got an over head tank of measurement 40 m $\times$ 25 m $\times$ 15 m. For how many days will the water in the tank last?

Answer 1

Water in overhead tank
$=(40\times 25\times 15)m^3$
$=(40\times 25\times 15\times 1,000\text{litres})$ [Since 1 cubic metre = 1000 litres]

Water required for 5,000 villagers for one day $=(5000\times 75)$ litres

The number of days the water in the tank will last
$=\frac{40\times 25\times 15\times 1000}{5000\times 75}=40$ days