several teams take part in a game
each of which must play one game with all other team

how many teams took part in competition if they played 45 games in all

Question

several  teams take part in  a game 
each of which must play one game with all  other team

how many teams took part  in competition if they played 45 games in all

wolfe8 · Answer

I think it would be $$P _{2}^{x}=45$$ How to solve that though... I think you'll have to rewrite it in extended form, which is not something I remember how to do right now.

wolfe8 · Answer

Alright so it's supposed to be $$_{15}C _{2}=45$$ This should help. Can you figure it out from the formula given? http://www.mathwords.com/c/combination_formula.htm

wolfe8 · Answer

Wait what lol it's x not 15. Dammit my typing/

anonymous · Answer

@wolfe8  : ok ok  i got it..

wolfe8 · Answer

Oh awesome. I was about to put what I found http://www.beatthegmat.com/finding-n-when-total-permutations-or-combinations-given-t24606.html