A set of football matches is to be organized in a "round-robin" fashion, i.e., every
participating team plays a match against every other team once and only once. If 10
matches are totally played, how many teams participated?
Choices
A) 4
B) 5
C) 10
D) 7
E) 8
2 ways to solve this problem..   summation(x)=n(n-1)/2   n(n-1)/2=10;   n^2-n-20=0   Ans : 5   ANSWER:5
<result>B</result>
A set of football matches is to be organized in a "round-robin" fashion, i.e., every
participating team plays a match against every other team once and only once. If 10
matches are totally played, how many teams participated?