Question

In a group of children each child gives a gift to every other child. If the number of gifts are $132$, find the number of children.

• A. $12$
• B. $18$
• C. $10$
• D. $16$

Answer 1

The correct option is A $12$

Let the total number of children be x.
Considering a child, he/she gives the gift to total of $(x-1)$ children.
Hence
$x(x-1)=132$
$x(x-1)=12.11$
Hence
$x=12$ and $x-1=11$
$x=12$
Hence 12 children in total.