Skilled and unskilled workers — Aptitude Question
Skilled and unskilled workers: The average wage of 30 workers is ₹500. Skilled workers earn ₹600 and unskilled ₹450. Answer and worked solution on CodeKairo.
- Topic: Mixtures & Alligation
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 60 seconds
Question
The average wage of 30 workers is ₹500. Skilled workers earn ₹600 and unskilled ₹450. How many workers are skilled?
Options
- 10
- 12
- 15
- 20
Show the answer and the worked solution
Correct answer: A. 10
Worked solution
- Skilled : unskilled = (500 − 450) : (600 − 500) = 50 : 100 = 1 : 2.
- Skilled = 1/3 × 30 = 10.
- Check: (10 × 600 + 20 × 450)/30 = 15,000/30 = 500. ✓
Answer: 10.
The idea
Any weighted-average question with two groups is an alligation. The group whose value is farther from the mean is the smaller group.
Shortcut. Each skilled worker is ₹100 above the mean and each unskilled ₹50 below, so balance needs two unskilled per skilled: 10 and 20.
Common trap. 20 — the unskilled count, from reading the 1 : 2 ratio the wrong way round; the skilled group, farther from the mean, is the smaller one.