Q. In a 30 litre mixture of milk and water, the ratio of milk and water is 7:3. How much water should be added in the mixture so that the ratio of milk and water becomes 3:7?
A) 5
B) 12
C) 28
D) 40
✔ Correct Answer: 40
Exam Insight
Initially, milk is 21 litres, and water is 9 litres. Let x litres of water be added. The equation becomes 21 / (9 + x) = 3 / 7. Solving this, x = 41 litres. Thus, 41 litres of water must be added.