Question

A container contains 40 litres of milk. From this container 4 litres of milk was taken and replaced by water. This process was repeated for two times. How much milk is now contained in the container?

• A. 26.34 litres
• B. 27.36 litres
• C. 28 litres
• D. 29.16 litres

Hint:

In such problems, apply the percentage reduction to the quantity after each replacement to calculate the final amount.

Answer 1

The Correct Option is D

Let the quantity of milk in the container after the first replacement be $x_1$.
Initially, there are 40 litres of milk in the container.
After the first operation, 4 litres of milk is removed and replaced with water.
The remaining amount of milk is: \[ x_1 = 40 \times \left(1 - \frac{4}{40}\right) = 40 \times \frac{9}{10} = 36 \text{ litres.} \] After the second operation, 4 litres of milk is again removed from 36 litres and replaced with water: \[ x_2 = 36 \times \left(1 - \frac{4}{40}\right) = 36 \times \frac{9}{10} = 32.4 \text{ litres.} \]
Thus, after the second replacement, the remaining milk in the container is 32.4 litres.