Problems on Ages — “A father (Sanyal) is three times his son’s present age. Six years hence, their ages will be in the ratio 5 : 2. Find Sanyal’s present age.”

Difficulty: Medium

Correct Answer: 54 years

Explanation:


Introduction / Context:
Parent–child age problems often give a present-time multiple and a future-time ratio. Setting the parent as a multiple of the child’s present age, then applying the future ratio, yields a single unknown variable to solve.


Given Data / Assumptions:

  • Let son = s; father (Sanyal) = 3s now.
  • After 6 years: (3s + 6) : (s + 6) = 5 : 2.


Concept / Approach:
Cross-multiply to obtain a linear equation in s; compute s and then Sanyal’s age 3s.


Step-by-Step Solution:

2(3s + 6) = 5(s + 6) ⇒ 6s + 12 = 5s + 30.Solve: s = 18.Sanyal now = 3s = 54 years.


Verification / Alternative check:
Six years later: father 60, son 24 ⇒ 60 : 24 = 5 : 2 ✓.


Why Other Options Are Wrong:
48/50/60/45 do not respect both the present multiple and the 5:2 future ratio when paired with a consistent son’s age.


Common Pitfalls:
Forgetting to add 6 to both ages; setting father = 3(s + 6) instead of 3s + 6 (the multiple applies to present ages only).


Final Answer:
54 years

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