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:

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Question

This question was previously asked in

RRB NTPC Graduate Level CBT-I Official Paper (Held On: 09 Jun, 2025 Shift 1)

Answer 1

Given:

Average weight of A, B, C = 45 kg

Average weight of A and B = 40 kg

Average weight of B and C = 42 kg

Formula used:

Average = (Sum of values) ÷ (Number of values)

Calculation:

⇒ A + B + C = 45 × 3 = 135

⇒ A + B = 40 × 2 = 80

⇒ B + C = 42 × 2 = 84

Now, add (A + B) and (B + C):

⇒ A + 2B + C = 80 + 84 = 164

We already have: A + B + C = 135

⇒ Subtract:

(A + 2B + C) − (A + B + C) = 164 − 135

⇒ B = 29

∴ The weight of B is 29 kg.

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