Q. 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 21 matches are totally played, how many teams participated?

Ans:7

• let n be the no. of teams then
  total matches played will be n(n-1)/2
  A/Q n(n-1)/2=21
  or n(n-1)=42=7*6
  or n=7
• 11 years agoHelpfull: Yes(0) No(1)
• nc2=21 so n=7
• 10 years agoHelpfull: Yes(0) No(1)