The average weight of three men A, B and C is 84 kg. Another man D joins the group and the average now becomes 80 kg. If another man E, whose weight is 3 kg more than that of D, replace A, then the average weight of B, C, D and E becomes 79 kg. The weight of A is:
Correct Answer: Option C
Let the weight of A be x kg.
Total weight of A, B and C = 84 × 3 = 252 kg
When D joins them, total weight of A, B, C and D = 80 × 4 = 320 kg
Thus, weight of D = 320 – 252 = 68 kg
Given: weight of E = weight of D + 3 kg = (68 + 3) kg = 71 kg
Total weight of B, C, D and E = 79 × 4 = 316 kg
Therefore, 320 – x + 71 = 316
⇒391 – x = 316
∴ x = 75
Thus, weight of A = 75 kg.
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