Question

In a Christmas celebrations, a family plays an event in which every person gives gift to every other person. If total number of gifts ordered by the family is $210$, then total number of persons in the family

• A. $15$
• B. $16$
• C. $12$
• D. $14$

Answer 1

The correct option is A $15$

Let total number of persons in celebration $=x$

Given that each person gifts every other person

Total number of gifts $=210=x(x-1)$

$210=x^2-x$

$x^2-x-210=0$

$x=15$