A family five years on — Averages Aptitude Question
A family five years on: The average age of a husband and wife was 23 years when they married. Answer and worked solution on CodeKairo.
- Topic: Averages
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 75 seconds
Question
The average age of a husband and wife was 23 years when they married. Five years later they have a one-year-old child. What is the average age of the family now?
Options
- 17
- 18
- 19
- 20
Show the answer and the worked solution
Correct answer: C. 19
Worked solution
- At marriage the couple's total age = 2 × 23 = 46.
- Five years later = 46 + 10 = 56.
- With the child: (56 + 1)/3 = 57/3 = 19.
Answer: 19.
The idea
Age the existing members forward by the same number of years each, then add the new member and divide by the new count.
Shortcut. The parents now average 23 + 5 = 28, so the family totals 2 × 28 + 1 = 57, and 57 ÷ 3 = 19.
Common trap. "17" — adding five years to the couple's total once instead of to each parent: (46 + 5 + 1) ÷ 3 ≈ 17.3.