Question
The average weight of (n + 1) girls is 50 kg, and the
average weight of (n - 3) boys is 70 kg. If the overall average weight is 62 kg, how many boys are there?Solution
ATQ: [(n + 1) × 50 + (n - 3) × 70] ÷ [(n + 1) + (n - 3)] = 62 Or, 50n + 50 + 70n - 210 = 62 × (2n - 2) Or, 120n - 160 = 124n - 124 Or, 4n = - 36 Or, n = -9 Hence solution is impossible
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