From a future age to a present one — Aptitude Question
From a future age to a present one: The ages of A and B are in the ratio 4 : 3. A will be 26 years old in 6 years. Answer and worked solution on CodeKairo.
- Topic: Problems on Ages
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 50 seconds
Question
The ages of A and B are in the ratio 4 : 3. A will be 26 years old in 6 years. What is B's present age?
Options
- 12
- 15
- 18
- 21
Show the answer and the worked solution
Correct answer: B. 15
Worked solution
- A is 26 − 6 = 20 now.
- A : B = 4 : 3, so B = 20 × 3/4 = 15.
Answer: 15.
The idea
Bring the given age back to the present first, then apply the ratio. Applying the ratio to the future age gives 19.5 and is wrong.
Shortcut. Take the six years off A first: 20 = 4 parts, so one part is 5 and B = 3 parts = 15. As a check, 20 : 15 reduces to 4 : 3.
Common trap. 21 is B's age in six years (15 + 6); answering for the moment the 26 refers to, instead of the present, gives it.