Lesson eLearning

If the roof of Chhotu House is a rectangle 8 m long and 5 m wide, and a rainfall of 40 mm falls, how many litres of rainwater can be collected from the roof? Assume the roof is 100% efficient.

medium 3 marks Class 3 · EVS · Chhotu House
Answer
1600

The correct answer is 1600 — Convert to litres: 1.6 m³ × 1000 L/m³ = 1600 L.

Step-by-step solution

  1. Compute roof area: 8 m × 5 m = 40 m².
  2. Convert rainfall: 40 mm = 0.04 m.
  3. Calculate volume: area × rainfall = 40 m² × 0.04 m = 1.6 m³.
  4. Convert to litres: 1.6 m³ × 1000 L/m³ = 1600 L.
Common mistake: confusing cubic metres with litres or forgetting unit conversion

Concept tested: rainwater harvesting calculation

Published · How this solution was prepared and checked

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