A 60-litre mixture has milk and water in the ratio 2 : 1. How much water must be added to make the ratio 1 : 2?

Problem restatement
Start with 60 L mixture where milk : water = 2 : 1. Add water to make milk : water = 1 : 2. Find the added water.

Given data

• Total initially = 60 L; milk = 40 L; water = 20 L.
• Add x litres of water.

Concept/Approach
Milk quantity stays 40 L; water becomes 20 + x. Set the target ratio 40 : (20 + x) = 1 : 2 and solve for x.

Step-by-step calculation
40 : (20 + x) = 1 : 2 ⇒ (20 + x) = 80 x = 80 − 20 = 60 L

Verification/Alternative
New amounts: milk 40 L, water 80 L → ratio 1 : 2. Total becomes 120 L.

Common pitfalls

• Changing the milk amount; only water is added.

Final Answer
60 litres