A container contains 330 litres of milk. Some quantity of milk is taken out and half of that quantity of milk, water is added in the container. Now ratio of milk to water in the container becomes 5:3. What is the quantity of water added in it?

Let x be the quantity of milk removed. Water added = x/2. Remaining milk = 330 - x. Final ratio (milk:water) = (330 - x) / (x/2) = 5/3. Cross-multiplying: 3(330 - x) = 5(x/2), so 990 - 3x = 2.5x, giving 990 = 5.5x, therefore x = 180. Water added = x/2 = 90 litres. Option A (80) is incorrect. Option C (120) would require x = 240, which is too much. Option D (60) would require x = 120.