Difference between revisions of "2012 AMC 8 Problems/Problem 14"
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− | This problem is very similar to a handshake problem. We use the formula <math> \frac{n(n | + | This problem is very similar to a handshake problem. We use the formula <math> \frac{n(n+1)}{2} </math> to usually find the number of games played (or handshakes). Now we have to use the formula in reverse. |
So we have the equation <math> \frac{n(n-1)}{2} = 21 </math>. Solving, we find that the number of teams in the BIG N conference is <math> \boxed{\textbf{(B)}\ 7} </math>. | So we have the equation <math> \frac{n(n-1)}{2} = 21 </math>. Solving, we find that the number of teams in the BIG N conference is <math> \boxed{\textbf{(B)}\ 7} </math>. |
Revision as of 00:03, 26 October 2015
Problem
In the BIG N, a middle school football conference, each team plays every other team exactly once. If a total of 21 conference games were played during the 2012 season, how many teams were members of the BIG N conference?
Solution
This problem is very similar to a handshake problem. We use the formula to usually find the number of games played (or handshakes). Now we have to use the formula in reverse.
So we have the equation . Solving, we find that the number of teams in the BIG N conference is .
See Also
2012 AMC 8 (Problems • Answer Key • Resources) | ||
Preceded by Problem 13 |
Followed by Problem 15 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | ||
All AJHSME/AMC 8 Problems and Solutions |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.