A group contains some number of members. If 2 members

Solution

ATQ,

Let the number of members in group and average weight of group be 'n' and 'm' kg, respectively.

So,

mn - 2 × 61 = (n - 2) × (m - 1)

Or, mn - 122 = mn - n - 2m + 2

Or, 2m + n = 124 --------- (I)

And,

mn - 3 × 62 = (n - 3) × (m - 2)

Or, mn - 186 = mn - 2n - 3m + 6

Or, 2n + 3m = 192 -------- (II)

On solving 3 × equation (I) - 2 × equation (II),

We get, 3 × (2m + n) - 2 × (2n + 3m) = 3 × 124 - 2 × 192

Or, 6m + 3n - 4n - 6m = 372 - 384

Or, -n = -12

Thus, 'n' = 12