Multiple choice

From a container having pure milk, 10% is replaced by water. This process was repeated thrice. At the time of third operation, the milk remained in the container is:

  1. 70% pure

  2. 90% pure

  3. 80% pure

  4. 72.90% pure
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is a successive replacement problem. Each operation replaces 10% of the mixture with water, so 90% of the previous mixture remains. After three operations: Remaining milk = 100% × (0.90)^3 = 100% × 0.729 = 72.9%. Option D (72.90% pure) is correct.

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