Arithmetichard · Past Paper

A vessel contains 40L milk. 4L is removed and replaced with water. This process is repeated once more. The final ratio of milk to water is:

A81:19
B9:1
C19:81
D8:1

✓ Correct Answer: A81:19

Final milk = 40 * (1 - 4/40)^2 = 40 * (0.9)^2 = 32.4L. Water = 40 - 32.4 = 7.6L. Ratio = 32.4 : 7.6 = 324 : 76 = 81 : 19.

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