Question
A container is completely filled with 30 litres of pure
milk. First, 40% of the mixture is removed and replaced with water. Then again 40% of the resulting mixture is removed and replaced with water. What is the final ratio of milk to water in the container?Solution
ATQ, Each time, 40% of the mixture is removed and replaced by water. Fraction of milk retained each time = 1 β 0.40 = 0.60. Initial milk = 30 L. After first operation: milk = 30 Γ 0.6 = 18 L. After second operation: milk = 18 Γ 0.6 = 10.8 L. Total = 30 L β water = 30 β 10.8 = 19.2 L. Ratio milk : water = 10.8 : 19.2 = 9 : 16.