The average weight of a group of

Solution

ATQ, Number of friends in the group = x Let the average weight of each friend be y kg Total weight of the group = x × y = xy kg First condition: (xy + 61) = (x + 1) × (y + 1) Or, xy + 61 = xy + y + x + 1 Or, y + x = 60 ----------- (I) Second condition: (xy + 60 + 58) = (x + 2) × (y + 1.5) Or, xy + 118 = xy + 2y + 1.5x + 3 Or, 2y + 1.5x = 115 ----------- (II) From (I): y = 60 – x Putting in (II), 2(60 – x) + 1.5x = 115 120 – 2x + 1.5x = 115 120 – 0.5x = 115 0.5x = 5 x = 10 So, value of x = 10