Unequal quantities poured together — Aptitude Question
Unequal quantities poured together: 10 litres of a 3 : 2 milk-and-water mixture is poured together with 15 litres… Answer and worked solution on CodeKairo.
- Topic: Mixtures & Alligation
- Section: Quantitative Aptitude
- Difficulty: Hard
- Time target: 105 seconds
Question
10 litres of a 3 : 2 milk-and-water mixture is poured together with 15 litres of a 2 : 3 mixture. What is the new ratio?
Options
- 2 : 3
- 3 : 2
- 12 : 13
- 13 : 12
Show the answer and the worked solution
Correct answer: C. 12 : 13
Worked solution
- First: milk = (3/5) × 10 = 6 L, water = 4 L.
- Second: milk = (2/5) × 15 = 6 L, water = 9 L.
- Totals: milk 12 L, water 13 L → 12 : 13.
Answer: 12 : 13.
The idea
Convert each vessel to actual litres before combining. Ratios cannot be added directly when the volumes differ.
Shortcut. Each vessel holds 6 L of milk (3/5 of 10, 2/5 of 15), so milk is 12 of the 25 litres: 12 : 13.
Common trap. "13 : 12" — working out the water first and writing water : milk, when the ratio asked for is milk to water.