Question 1193292
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The statement of the problem does not make it absolutely clear; but I will assume each of the 13 people is on one team or the other.<br>
So to form the teams, we can choose some number out of the 13 to be on one team, and the ones not chosen form the other team.<br>
For example, if the first team chosen has 5 players, then the number of ways of forming the two teams is 13C5.<br>
Then, since the first team chosen can have any number of players, the total number of ways of forming the two teams is<br>
13C0 + 13C1 + 13C2 +...+ 13C12 + 13C13 = 2^13 = 8192<br>
However, presumably a "team" with 0 players would not be considered a team, so the requirement of "2 teams total" would not be satisfied.  So the number of ways of forming 2 teams from 13 players (eliminating the cases where the first team is made up of either 0 or 13 players) is<br>
13C1 + 13C2 +...+ 13C12 = 8192-2 = 8190.<br>
ANSWER: 8190<br>