Milkman's profit from water — Aptitude Question
Milkman's profit from water: A milkman mixes water with milk in the ratio 1 : 4 and sells the mixture at cost price. Answer and worked solution on CodeKairo.
- Topic: Mixtures & Alligation
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 90 seconds
Question
A milkman mixes water with milk in the ratio 1 : 4 and sells the mixture at cost price. What is his profit percent?
Options
- 20%
- 25%
- 30%
- 33⅓%
Show the answer and the worked solution
Correct answer: B. 25%
Worked solution
- Take 4 L of milk and 1 L of water: 5 L of mixture.
- He pays for 4 L but receives the price of 5 L.
- Profit = 1/4 = 25%.
Answer: 25%.
The idea
The gain is the free component measured against the cost of what was bought, not against the mixture sold. Dividing by 5 instead of 4 gives 20%, which is offered.
Shortcut. Read it off the ratio: 1 L of free water per 4 L of paid milk is a 1/4 = 25% gain; a 1 : 3 mix would give 33⅓%.
Common trap. 20% — measuring the free litre against the 5 L of mixture instead of the 4 L he paid for.