Difficulty: Easy
Correct Answer: 6
Explanation:
Introduction / Context:Age-ratio problems are solved by forming an equation on future ages. Linear growth by n years preserves differences but changes ratios; we equate the target ratio and solve for n directly.
Given Data / Assumptions:
Concept / Approach:Write (36 + n)/(50 + n) = 3/4 and cross-multiply to obtain a simple linear equation in n. Ensure the solution is feasible (age cannot be negative, but here it is clearly positive).
Step-by-Step Solution:
(36 + n)/(50 + n) = 3/44(36 + n) = 3(50 + n)144 + 4n = 150 + 3n ⇒ n = 6Verification / Alternative check:After 6 years: ages are 42 and 56. Ratio 42:56 simplifies to 3:4, confirming the result.
Why Other Options Are Wrong:
Common Pitfalls:Accidentally using (50 − n) or mixing up who is older. Always add n to both ages for “after n years.”
Final Answer:6
Discussion & Comments