Hi LUANDATO,

We're told that a kickball competition has 9 teams in it. We're asked for the number of possible matches that can be played between 2 teams. This question can be solved in a variety of ways, including simply listing out the possibilities for each team.

Let's call the teams ABCDE FGHI
Team A plays all 8 teams, so that's 8 games
Team B already played Team A, so Team B could play 7 additional games
Team C already played Teams A and B, so Team C could play 6 additional games.

Notice how the number of 'new' games decreases by 1 with each team. That means the total number of possible games would be:

8+7+6+5+4+3+2+1+0 = 36 possible games

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

BTGmoderatorLU wrote:In a kickball competition of 9 teams, how many possible matches can each team play which each other?

(A) 9
(B) 16
(C) 24
(D) 36
(E) 54

The OA is D.

I'm really confused with this PS question because if there are 9 teams, each team can play a single game with each other, I don't understand it. Experts, any suggestion? Thanks in advance.

The total possible number of matches is 9C2 = (9 x 8)/2 = 36.

Answer: D