Four more than four times — Aptitude Question
Four more than four times: A father's present age is 4 more than four times his son's. After 4 years he will be 2… Answer and worked solution on CodeKairo.
- Topic: Problems on Ages
- Section: Quantitative Aptitude
- Difficulty: Hard
- Time target: 120 seconds
Question
A father's present age is 4 more than four times his son's. After 4 years he will be 2 more than three times his son's age. What is the father's present age?
Options
- 24
- 28
- 32
- 36
Show the answer and the worked solution
Correct answer: B. 28
Worked solution
- f = 4s + 4.
- f + 4 = 3(s + 4) + 2 = 3s + 14 → 4s + 8 = 3s + 14 → s = 6.
- f = 4 × 6 + 4 = 28.
- Check: in 4 years, 32 and 10, and 3 × 10 + 2 = 32. ✓
Answer: 28.
The idea
Translate each sentence into an equation exactly as written, including the '+ 4' and '+ 2' constants. Then substitute one into the other.
Shortcut. Back-substitute: each option gives the son as (f − 4) ÷ 4. For 28 the son is 6, and in four years 32 = 3 × 10 + 2. 24 (son 5) gives 28 against 29 and fails.
Common trap. 32 is the father's age after four years (28 + 4); solving correctly and reading off the future age instead of the present one gives it.