1, the straight line length is 85.96m, the diameter of the innermost semicircular runway is 72.6m, and the width of each runway is1.25m.. How many meters should the starting line of each runway be different?

2. 10 Students take part in the checkers competition organized by the school. Every two students must play a game. How many games will a * * * play if the single round robin system is adopted? If the elimination system is adopted, how many games will be needed to decide the third place in the championship; How many games will the champion, second place and third place play?

Solution: 1, if it is a 400-meter race, the distance difference between two runners running a full lap should be the difference between the starting lines. Because the straight parts are equal in length, only the semicircular parts on both sides are considered. (72.6+ 1.25*2)π - 72.6π =2.5 π=7.85

2. Single round robin system. Every student has to compete with every player except himself for a game of 10*9=90.

The competition between A and B and A is actually the same thing, so every game is repeated. 90/2=45 games

Single round robin system. Number of games = number of participants * (number of participants-1)/2

Elimination of the competition number determines the champion, runner-up and runner-up = number of participants-1

Decide the top three games = number of participants