Difficulty: Easy
Correct Answer: 5 : 4
Explanation:
Introduction / Context:Given a present-time ratio and total, we can compute individual ages. Then add the same future increment to each and simplify the new ratio.
Given Data / Assumptions:
Concept / Approach:Let ages be 4k and 3k. Using the sum, find k. Then compute (4k + 4):(3k + 4) and reduce if needed.
Step-by-Step Solution:
4k + 3k = 28 ⇒ 7k = 28 ⇒ k = 4.Now: N = 16, D = 12.After 4 years: 20 : 16 = 5 : 4.Verification / Alternative check:Dividing both terms by 4 gives 5 : 4; consistent.
Why Other Options Are Wrong:Other ratios do not reflect the correct incremented pair (20, 16).
Common Pitfalls:Applying the 4-year increment to only one person or rescaling the ratio incorrectly before adding years.
Final Answer:5 : 4
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