The average weight of 10 boys is increased by 3 kg if one of them weighing 40 kg is replaced by a new boy. The weight of the new boy is:
70 kg
Given:
Average weight of 10 boys.
Increase in average weight = 3 kg.
Weight of the boy being replaced = 40 kg.
Concept:
Change in average × Number of data points = Change in total weight.
Solution:
For 10 boys, the total weight increase due to the 3 kg average increase ⇒ 3 kg × 10 = 30 kg.
Difference in weight between the new boy and the boy being replaced ⇒ 30 kg + 40 kg (weight of the boy being replaced) = 70 kg.
Therefore, the weight of the new boy is 70 kg.
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