Given details are,
Population of village = 4000
Dimensions of water tank = 20m × 15m × 6m
Water required per head per day = 150 litres
Total requirement of water per day = 150 × 4000 = 600000 litres
Volume of water tank = l × b × h
= 20 × 15 × 6
= 1800m3
= 1800000 litres
We know that,
Number of days water last in the tank = volume of tank / total requirement
= 1800000/600000
= 3 days
∴ Water in the tank last for 3 days.
