How to calculate the probability of drawing lots in NBA draft?

Many procedures and rules of NBA draft are still like "seeing flowers in the fog" for some China fans. According to the time division, the annual NBA draft can be roughly divided into two parts. The first part is the draft lottery: the NBA began to implement the draft lottery from 1985. Every year when the playoffs are in full swing, the NBA will convene teams that fail to enter the playoffs to hold a lottery ceremony to determine the ownership of the top three draft picks in the future. In the lucky draw ceremony, the host will take out 1- 14 ping-pong balls and put them into the container. Four balls are randomly selected from 14 balls, regardless of numerical order. A * * can produce 100 1 possible combinations. Before the draw, the teams that didn't qualify for the playoffs had been ranked in reverse order according to the regular season record, and the corresponding combination number (probability) of winning the first prize was obtained. For example, 14 teams failed to make the playoffs this year. In this 14 team, the eagle with the worst record got 250 combinations, that is, there was a 25% chance to win the first place, and the wasp with the second worst record got 199, that is, 19.9% chance, and so on,/kloc-0.9%. After the draw for No.1 draft, four table tennis balls were put back into the container, and the ownership of No.2 and No.3 draft picks was decided again. After that, the remaining No.4-30 draft picks in the first and second rounds were decided in reverse order according to the results of the regular season.