Date: Feb 5, 2013 2:20 PM Author: Ray Koopman Subject: Re: how many ways to pick two teams of 10 out of a group of 20 people On Feb 4, 11:45 pm, G Patel <gaya.pa...@gmail.com> wrote:

> Is it 20 choose 10 or do I have to divide by 2?

If the teams are distinguishable -- e.g., if one is the "home" team

and the other is the "visiting" team -- then it's 20_choose_10.

But if there is no such distinction then you divide that by 2.