150% of his age eight years ago — Aptitude Question
150% of his age eight years ago: A man's present age is 150% of his age 8 years ago. What is his present age? Answer and worked solution on CodeKairo.
- Topic: Problems on Ages
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 75 seconds
Question
A man's present age is 150% of his age 8 years ago. What is his present age?
Options
- 16
- 20
- 24
- 28
Show the answer and the worked solution
Correct answer: C. 24
Worked solution
- a = 1.5(a − 8) = 1.5a − 12.
- 0.5a = 12 → a = 24.
- Check: eight years ago he was 16, and 150% of 16 is 24. ✓
Answer: 24.
The idea
Turn the percentage into a multiplier and write one equation. A percentage above 100 always makes the coefficient of a larger on the right, so collect on that side.
Shortcut. 150% means present : past = 3 : 2. The one-part gap is the 8 years, so the present age is 3 × 8 = 24.
Common trap. 16 comes from expanding 1.5(a − 8) as 1.5a − 8, dropping the 1.5 on the 8; it is also his age eight years ago, so it feels doubly right.