Ages from ratio and product: The present age ratio of father and son is 7 : 4, and the product of their present ages is 1008. What will be their age ratio after 6 years?

Difficulty: Easy

Correct Answer: 8 : 5

Explanation:


Introduction / Context:
Given a ratio and a product, we find the common multiplier by taking the square root after factoring properly. Once current ages are known, adding 6 to both yields the future ratio.


Given Data / Assumptions:

  • Father : Son = 7 : 4
  • Product = 1008
  • Find ratio after 6 years


Concept / Approach:
Let ages be 7x and 4x. Then 28x^2 = 1008 gives x. Compute current ages, add 6 to both, and simplify the ratio.


Step-by-Step Solution:

7x * 4x = 28x^2 = 1008 ⇒ x^2 = 36 ⇒ x = 6Father now = 42, Son now = 24After 6 years ⇒ 48 : 30 = 8 : 5


Verification / Alternative check:
Product check: 42 * 24 = 1008; ratio update is correct after equal increments of 6 years.


Why Other Options Are Wrong:
5 : 3 and 7 : 4 are not the future ratio; 5 : 8 reverses the order and is incorrect.


Common Pitfalls:
Forgetting that adding the same years to both changes the ratio unless both ages are equal initially.


Final Answer:
8 : 5

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