Q. There were two women participating in a chess tournament. Every participant played two games with the other participants. The number of games that the men played between themselves proved to exceed by 66 the number of games that the men played with the women. The number of participants is

A) 6
B) 11
C) 13
D) None of these
Explanation

(c)
Let there be $'n$’ men participants. Then, the number of games that the men play between themselves is 2. $\ ^{n}C_{2}$ and the number of games that the men played with the women is $2.(2n)$
$\therefore\ 2.{\ ^{n}C}_{2} - 2.2n = 66$ (given)
$\Rightarrow n(n - 1) - 4n - 66 = 0$
$\Rightarrow n^{2} - 5n - 66 = 0$
$\Rightarrow (n + 5)(n - 11) = 0$
$\Rightarrow n = 11$
$\therefore$ Number of participants =11 men+2 women=13

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.