Fifteen years hence, five times five back — Aptitude
Fifteen years hence, five times five back: A man's age after 15 years will be five times his age 5 years ago. Answer and worked solution on CodeKairo.
- Topic: Problems on Ages
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 60 seconds
Question
A man's age after 15 years will be five times his age 5 years ago. What is his present age?
Options
- 8
- 10
- 12
- 15
Show the answer and the worked solution
Correct answer: B. 10
Worked solution
- r + 15 = 5(r − 5) = 5r − 25 → 4r = 40 → r = 10.
- Check: in 15 years he is 25, and five years ago he was 5. ✓
Answer: 10.
The idea
Translate 'after' as +, 'ago' as −, and 'times' as multiplication of the whole bracket. The rest is one linear equation.
Shortcut. The two moments are 15 + 5 = 20 years apart and the later age is five times the earlier, so the 20 years are four parts: he was 5 then and is 10 now.
Common trap. 15 tempts because it echoes the question's fifteen years, but it gives 30 after fifteen years against 10 five years ago — only three times, not five.