Exams › SSC CGL (Prelims) › General

From a 54-litre container of pure milk, 9 litres are removed and replaced by water. This process is repeated three times in total. What is the final quantity of milk left in the container?

1. 30.37 litres
2. 31.25 litres
3. 34.29 litres
4. 36.10 litres

Correct answer: 31.25 litres

Solution

In each step, the fraction of milk left is \(\frac{54-9}{54}=\frac{5}{6}\). After 3 repetitions, milk left = \(54\left(\frac{5}{6}\right)^3\). This equals 31.25 litres.

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