Combinations / Variations ( Basic probability )

[markus.dnd]

Hello. I got a math problem. ( It should be easy for most of the people. Even me but i missed the class when they were looking at that)

 

On a chess tournament every chess player played one time with every one. in total there were 45 chess games held. How many players were there?

 

I just can not figure out what i should use and how to find the number of players.

 

EDIT: I allready got it. I have to use Combinations formula and it all works out

Before i just could not find the right way to use it. But still if someone got good ideas to use for this i'd like to hear them.

Edited November 3, 2008 by markus.dnd
Finished it myself

[hermanntrude]

doesnt the formula for combinations involve factorials? How do you do the reverse of a factorial?

[Mr Skeptic]

You just have to rephrase the question. If you have n players who play a game with every other player, how many games would they play? Then just work backwards from 45 games. I'd say its about ten players