Puzzleup 2014 (15) Chess Players - 西洋棋

題目網址: http://www.puzzleup.com/2014/
http://www.puzzleup.com/2014/puzzle/?256

答題時限: 11月６日７ＰＭ－比賽結束（約12月17日）
加分時限: 11月６日７ＰＭ－11月12日６：５９ＰＭ

答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　
比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　 　　 　　
另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　

◆Chess Players

There are 24 players in a chess tournament. 8 teams participated with 2
players , and 8 teams participated with 1 player. For the 12 matches in the
first round, the pairings will be drawn randomly. What is the probability
that at least 4 matches will be played between players from the same team?

Enter your answer as a simplified fraction. Example:12/23

在一場西洋棋比賽中有 24 位參賽者。

有八個隊伍有兩人參賽，另外八個隊伍有一人參賽。

第一回合的十二場比賽的對陣是隨機決定的。

試問這當中存在至少四場比賽為來自同隊伍的人對戰的機率為何？

答案以最簡分數輸入，如 12/23。

--
LPH [acronym]
= Let Program Heal us
-- New Uncyclopedian Dictionary, Minmei Publishing Co.

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