Average weight of a group of ‘x’ people increased by 2

Solution

Number of people in the group = ‘x’Let, average weight of each person in the group be ‘y’ kg
Total weight of all the persons in the group = x × y = ‘xy’ kg
ATQ,
(xy + 68) = (x + 1) × (y + 2)
Or, xy + 68 = xy + y + 2x + 2
Or, y + 2x = 66 ------------(I)
Also,
(xy + 66 × 2) = (x + 2) × (y + 3)
Or, xy + 132 = xy + 2y + 3x + 6
Or, 2y + 3x = 126 ------------(II)
Putting value of ‘y’ from equation (I) in equation (II), we get
y = 66 – 2x
So, 2(66 – 2x) + 3x = 126
Or, 132 – 4x + 3x = 126
Or, –x = –6
So, x = 6
So, value of ‘x’ = 6