Question
The average weight of a group of NN children is (N+1)(N
+ 1) kg. When a child weighing 36.5 kg leaves the group, the average weight decreases by 0.5 kg. Determine the original number of children in the group.Solution
Sum of the weights of 'N' children = N X (N + 1) = (N2 + N) kg ATQ, (N2 + N - 36.5) ÷ (N - 1) = N + 1 - 0.5 Or, N2 + N - 36.5 = (N - 1) X (N + 0.5) Or, N2 + N - 36.5 = N2 + 0.5N - N - 0.5 Or, 15N = 360 So, 'N' = 24 Therefore, initial number of children in the group = 'N' = 24
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