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Arithmetic
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RRB NTPC Graduate Tier 1 2025 Shift-1 📅 09 Jun, 2025

The average weight of A, B and C is 45 kg. If the average weight of A and B is 40 kg and that of B and C is 42 kg, then the weight of B (in kg) is:

A
39
B
44
C
29
D
19
Result Summary
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RRB NTPC Graduate Tier 1
2025 • 09 Jun, 2025 • Shift-1
The average weight of A, B and C is 45 kg. If the average weight of A and B is 40 kg and that of B and C is 42 kg, then the weight of B (in kg) is:
Correct Answer
29
Aggregate Sum Formulation: By definition, the total sum equals the average multiplied by the number of entities. The total combined weight of A, B, and C is 45 ......
Ref/Book : RRB NTPC Graduate Tier 1 2025
Ref. Subject Arithmetic
Chapter -
Ref. Topic Average
Pg. No -
💡 Analysis & Explanation
Aggregate Sum Formulation ▼
By definition, the total sum equals the average multiplied by the number of entities. The total combined weight of A, B, and C is 45 * 3 = 135 kg. So, mathematically, A + B + C = 135.
Deconstructing Sub-groups ▼
Analyzing the paired averages provides specific sub-sums. The sum of weights of A and B is 40 * 2 = 80 kg (A + B = 80). The sum of weights of B and C is 42 * 2 = 84 kg (B + C = 84).
Overlapping Isolation Strategy ▼
If we add the two sub-sums together, (A + B) + (B + C), we get A + 2B + C = 80 + 84 = 164. We observe that 'B' is counted twice in this new total. To isolate the exact weight of B, we strategically subtract the true sum of all three distinct individuals (A + B + C) from this overlapping total.
Final Execution ▼
B = (A + 2B + C) - (A + B + C) = 164 - 135 = 29.
Conclusion ▼
The individual isolated weight of B is exactly 29 kg.
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