Population two years ago — Percentages Aptitude Question
Population two years ago: The population of a town is 176,400 and grows at 5% per annum. What was it two years ago? Answer and worked solution on CodeKairo.
- Topic: Percentages
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 60 seconds
Question
The population of a town is 176,400 and grows at 5% per annum. What was it two years ago?
Options
- 1,50,000
- 1,60,000
- 1,64,000
- 1,68,000
Show the answer and the worked solution
Correct answer: B. 1,60,000
Worked solution
- 1.05² = 1.1025.
- Population two years ago = 176,400 ÷ 1.1025 = 1,60,000.
- Check: 160,000 → 168,000 → 176,400. ✓
Answer: 1,60,000.
The idea
Growth forwards multiplies; going backwards divides. Subtracting 10% from the present figure is not the inverse of two 5% rises.
Shortcut. Check the options forwards: 1,60,000 × 1.05 = 1,68,000, then × 1.05 = 1,76,400 — an exact match, no division by 1.1025 needed.
Common trap. "1,68,000" — going back only one year (176,400 ÷ 1.05) and stopping there.