Difficulty: Medium
Correct Answer: 59
Explanation:
Introduction:
When multiple averages over overlapping pairs and a triple are given, add the pair sums and compare with the triple sum to isolate the shared person's value. This uses linear relationships among sums efficiently.
Given Data / Assumptions:
Avg(S, G, R) = 97 ⇒ S + G + R = 291. Avg(S, G) = 93 ⇒ S + G = 186. Avg(G, R) = 82 ⇒ G + R = 164.
Concept / Approach:
Add (S + G) and (G + R) to get S + 2G + R, which equals (S + G + R) + G. Compare with the triple sum to solve for G.
Step-by-Step Solution:
(S + G) + (G + R) = 186 + 164 = 350. But S + 2G + R = (S + G + R) + G = 291 + G. Therefore, 350 = 291 + G ⇒ G = 59.
Verification / Alternative check:
Compute S = 186 − 59 = 127 and R = 164 − 59 = 105. Check: 127 + 59 + 105 = 291 and averages match the given values.
Why Other Options Are Wrong:
72, 56, 63, 61: Substituting any of these for G breaks one or more of the provided average relationships.
Common Pitfalls:
Trying to average the three given averages directly or solving for the wrong variable first. Focus on sums: pair sums vs triple sum lets you isolate G quickly.
Final Answer:
The weight of Gopesh is 59 kg.
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