In a village, there are 4 stagnant pools each with 300 litres of water. A mosquito species lays eggs at a rate of 0.8 egg per litre per day for 7 days. After hatching, each larva consumes 2 ml of water before becoming a pupa. If all eggs hatch and all larvae survive, how many litres of water will be left after 7 days?

Step-by-step solution

1. Step 1: Eggs laid per day per pool = 0.8 × 300 = 240 eggs.
2. Step 2: Total eggs per day for 4 pools = 240 × 4 = 960 eggs.
3. Step 3: Over 7 days, total eggs = 960 × 7 = 6,720 eggs.
4. Step 4: Total water consumed by larvae = 6,720 × 2 ml = 13,440 ml = 13.44 litres.
5. Step 5: Initial total water = 4 × 300 litres = 1,200 litres.
6. Step 6: Remaining water = 1,200 litres – 13.44 litres = 1,186.56 litres.

Concept tested: Calculation of water loss due to mosquito larvae

Published 10 October 2026 · How this solution was prepared and checked