SOLUTION: In a round robin tournament, each team plays every other team once. The formula G=n(n-1)/2 gives the number of games G that must be scheduled for n teams. Will the number of game

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Question 1153615: In a round robin tournament, each team plays every other team once. The formula G=n(n-1)/2 gives the number of games G that must be scheduled for n teams.
Will the number of games double if the number of teams doubles? Justify your answer.

Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!

If there are n teams, G(n) = n(n-1)/2
If there are m=2n teams, G(m) = m(m-1)/2 = 2n(2n-1)/2 = n(2n-1) games
The difference is
+n%282n-1%29+-+n%28n-1%29%2F2+=+%282n%282n-1%29+-+n%28n-1%29%29%2F2+=+%283n%5E2-n%29%2F2+
So, NO, the number of games does not double, it increasses by +%28n%283n-1%29%29%2F2+ when n doubles.

Example:
G(6) = 6(5)/2 = 15
G(12) = 12(11)/2 = 66
The difference is 66-15 = 51
and for n=6: n(3n-1)/2 = 6(3*6-1)/2 = 6(17)/2 = 51, as derived above.
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To the student: sorry just noticed your additional question in the 'thank you' message: it means when you double the number of teams, the number of games goes up by +%283n%5E2-n%29+%2F2+ or we can say (roughly) "if the number of teams doubles, the number of games needed goes up on the order of n%5E2". In the example I gave, n=6, G(n)=15 then I doubled the number of teams to 12 and showed G(12) = 66 so you can see the number games went up by a factor of 66/15 or 4.4. 4.4 is _roughly_ (on the same order of magnitude as) 2%5E2
Forgot to say... so yes, for doubling teams, you roughly quadruple the # of games needed for the RR.