Ages (two time-slices with ratios): Two years ago, Ram : Mohan = 3 : 2. At present, Ram : Mohan = 7 : 5. Find their present ages.

Difficulty: Medium

Correct Answer: 14 years, 10 years

Explanation:


Introduction / Context:
This problem gives ratios at two different time points, which is neatly handled by parameterizing the earlier ages and then advancing each by the same elapsed time.


Given Data / Assumptions:

  • Two years ago: (R − 2) : (M − 2) = 3 : 2.
  • Now: R : M = 7 : 5.


Concept / Approach:
Let R − 2 = 3k and M − 2 = 2k. Then R = 3k + 2, M = 2k + 2. Impose the present ratio to solve for k.


Step-by-Step Solution:

1) Set R = 3k + 2 and M = 2k + 2. 2) Apply present ratio: (3k + 2) / (2k + 2) = 7 / 5. 3) Cross-multiply: 5(3k + 2) = 7(2k + 2) → 15k + 10 = 14k + 14 → k = 4. 4) Present ages: R = 3*4 + 2 = 14 years; M = 2*4 + 2 = 10 years.


Verification / Alternative check:
Two years ago they were 12 and 8, which reduce to 3 : 2; now they are 14 and 10 → 7 : 5.


Why Other Options Are Wrong:
They violate one of the two ratio constraints when checked.


Common Pitfalls:
Forgetting to add the same 2 years to both persons, or swapping roles of Ram and Mohan when mapping ratios.


Final Answer:
14 years, 10 years

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