Difficulty: Medium
Correct Answer: 3 : 5
Explanation:
Introduction / Context:
Two hypothetical transfers create two linear conditions on the initial counts. Solving them yields the initial numbers and hence their ratio.
Given Data / Assumptions:
Concept / Approach:
Translate each scenario into an equation, then solve the pair for R and G. Finally reduce R:G to simplest form.
Step-by-Step Solution:
From scenario 2: R + 5 = G − 5 ⇒ G = R + 10.Substitute in scenario 1: (R + 10 + 5) = 3(R − 5) ⇒ R + 15 = 3R − 15.30 = 2R ⇒ R = 15; hence G = R + 10 = 25.Initial ratio R:G = 15:25 = 3:5.
Verification / Alternative check:
Check scenario 1: after transfer, R = 10, G = 30 ⇒ G is thrice R. Scenario 2: after transfer, both have 20 ⇒ equal.
Why Other Options Are Wrong:
1:3, 5:7, 7:9, 2:3 do not satisfy both transfer conditions simultaneously.
Common Pitfalls:
Placing the “give 5” on the wrong side; forgetting to update both people's counts in each scenario.
Final Answer:
3 : 5
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