A container contains 100 litres of water. 20 litres are withdrawn and replaced with pure milk. Then 20 litres of the mixture are withdrawn and replaced with milk. What is the final quantity of water remaining in the container?
Answer and explanation
Correct answer: A. 64 litres
- Step 1: Formula: Remaining water = Initial * (1 - x/V)^n.
- Step 2: Initial = 100, x = 20, V = 100, n = 2.
- Step 3: Remaining water = 100 (1 - 20/100)^2 = 100 (0.8)^2 = 100 * 0.64 = 64 litres.
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