A village, having a population of 4000, requires 150 litres of water per head per day. It has a tank measuring 20m × 15m × 6m. For how many days will the water of this tank last?

Given:
→l × b × h = 20 × 15 × 6
→Capacity of tank = l × b × h = (20 × 15 × 6)m³ = 1800m³ = 1800000 litre
→Consumption of water in 1 day = 4000 × 150 litres = 600000 litres
→Water of this tank will last for = 1800000 / 600000 = 3 days