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HMMT 十一月 2018 · GEN 赛 · 第 2 题

HMMT November 2018 — GEN Round — Problem 2

专题
Discrete Math / 离散数学
难度
L3
来源
HMMT

题目详情

  1. Twenty-seven players are randomly split into three teams of nine. Given that Zack is on a different team from Mihir and Mihir is on a different team from Andrew, what is the probability that Zack and Andrew are on the same team?
解析
  1. Twenty-seven players are randomly split into three teams of nine. Given that Zack is on a different team from Mihir and Mihir is on a different team from Andrew, what is the probability that Zack and Andrew are on the same team? Proposed by: Yuan Yao 8 Answer: 17 Once we have assigned Zack and Mihir teams, there are 8 spots for more players on Zack’s team and 9 for more players on the third team. Andrew is equally likely to occupy any of these spots, so our 8 answer is . 17