Multiple choice

A milkman has 100 litres of milk in an urn. He takes out 10 litres of milk from the urn and replaces it with water. He repeats this process three more times. What quantity of milk is present in the urn now?

  1. 65.61 litres

  2. 75.71 litres

  3. 80 litres

  4. 70 litres

  5. 60 litres
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A Correct answer
Explanation

The formula for remaining quantity is Initial * (1 - removed/total)^n. Here, 100 * (1 - 10/100)^4 = 100 * (0.9)^4 = 100 * 0.6561 = 65.61.

AI explanation

Use the formula for successive replacement: Final Quantity = Initial Quantity multiplied by (1 - Fraction Removed) raised to the Number of Operations. Here, the initial quantity is 100 litres, the fraction removed is 0.10, and the process is repeated 4 times. The remaining milk is 100 multiplied by (0.90)^4, which equals 100 multiplied by 0.6561, yielding 65.61 litres.

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