Question : The average weight of A, B, and C is 77 kg. If the average weight of A and B is 68 kg and that of B and C is 83 kg, then the weight (in kg) of B is:
Option 1: 74
Option 2: 71
Option 3: 73
Option 4: 67
Correct Answer: 71
Solution :
Given,
The average weight of A, B and C is 77 kg.
The average weight of A and B is 68 kg and that of B and C is 83 kg.
We know,
Total = average × number of items
⇒ Total weight of A, B, and C = 77 × 3
= 231 kg ............(1)
Total weight of A and B = 68 × 2
= 136 kg .............(2)
And, Total weight of B and C = 83 × 2
= 166 kg ..............(3)
From the formed equations,
Total weight of A and B + Total weight of B and C – Weight of B = Total weight of A, B, and C
⇒ 136 + 166 – Weight of B = 231
⇒ Weight of B = 302 – 231
⇒ Weight of B = 71 kg
Hence, the correct answer is 71 kg.
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