Average cost of three items — Aptitude Question
Average cost of three items: 5 kg at ₹40, 10 kg at ₹50 and 5 kg at ₹80 are mixed. What is the cost per kg of the… Answer and worked solution on CodeKairo.
- Topic: Mixtures & Alligation
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 75 seconds
Question
5 kg at ₹40, 10 kg at ₹50 and 5 kg at ₹80 are mixed. What is the cost per kg of the mixture?
Options
- ₹50
- ₹52
- ₹55
- ₹58
Show the answer and the worked solution
Correct answer: C. ₹55
Worked solution
- Cost = 5 × 40 + 10 × 50 + 5 × 80 = 200 + 500 + 400 = ₹1,100.
- Weight = 5 + 10 + 5 = 20 kg.
- Cost per kg = 1,100 ÷ 20 = ₹55.
Answer: ₹55.
The idea
Weighted average across three components: total cost divided by total weight.
Shortcut. Measure from ₹50: 5 kg at −10 and 5 kg at +30 net +100 over 20 kg, lifting the price by ₹5 to ₹55.
Common trap. "₹58" — averaging the three prices, (40 + 50 + 80) ÷ 3 ≈ 56.7, and taking the nearest option, ignoring that twice as much sits at ₹50.