Average monthly income — Averages Aptitude Question
Average monthly income: A man's average monthly expenditure for the first 3 months was ₹2,200 and for the next 9… Answer and worked solution on CodeKairo.
- Topic: Averages
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 90 seconds
Question
A man's average monthly expenditure for the first 3 months was ₹2,200 and for the next 9 months ₹1,800. He saved ₹1,200 during the year. What was his average monthly income?
Options
- ₹1,900
- ₹2,000
- ₹2,100
- ₹2,200
Show the answer and the worked solution
Correct answer: B. ₹2,000
Worked solution
- Spending = 3 × 2,200 + 9 × 1,800 = 6,600 + 16,200 = ₹22,800.
- Income = spending + savings = 22,800 + 1,200 = ₹24,000.
- Average monthly income = 24,000 ÷ 12 = ₹2,000.
Answer: ₹2,000.
The idea
Income = expenditure + savings over the same period. Work out the annual figures, then divide by 12 once at the end.
Shortcut. The average monthly spend is 1,800 + 400 × 3/12 = ₹1,900, and the savings add 1,200 ÷ 12 = ₹100 a month: ₹2,000.
Common trap. "₹1,900" — the average monthly expenditure, forgetting to add the ₹100 a month he saved.