Question

In a group of children , each child gives a gift to every other child . If the number of gifts is 132 , then find the no. Of children .

Answer 1

Let there are N children,then each of them will give (N-1) gifts,(each children will not gift himself)

Total gifts =N*(N-1) =N^2 -N

N^2 -N =132

N^2 -N -132 =0

(N-12)(N+11) =0

N = 12 ,-11

as number of children can not be negative,

so number of children =12