One year ago and four years hence — Aptitude Question
One year ago and four years hence: One year ago the ages of two people were in the ratio 5 : 6. Answer and worked solution on CodeKairo.
- Topic: Problems on Ages
- Section: Quantitative Aptitude
- Difficulty: Hard
- Time target: 120 seconds
Question
One year ago the ages of two people were in the ratio 5 : 6. Four years hence the ratio will be 6 : 7. What is the present age of the younger?
Options
- 24
- 25
- 26
- 30
Show the answer and the worked solution
Correct answer: C. 26
Worked solution
- Ages one year ago: 5x and 6x. Four years hence: 5x + 5 and 6x + 5.
- (5x + 5)/(6x + 5) = 6/7 → 35x + 35 = 36x + 30 → x = 5.
- One year ago the younger was 25, so now 26.
Answer: 26.
The idea
Anchor the variable at whichever moment the question describes first, then step forward carefully — from 'one year ago' to 'four years hence' is five years, not four.
Shortcut. Each ratio has a one-part gap, so the part size is fixed: over the five years the younger climbs from 5 parts to 6, so one part = 5 years. He was 25 a year ago and is 26 now.
Common trap. 25 is the younger's age one year ago (5 × 5) — the right x, but the one year is never added back to reach the present.