返回题库

HMMT 二月 2001 · 冲刺赛 · 第 23 题

HMMT February 2001 — Guts Round — Problem 23

专题
Discrete Math / 离散数学
难度
L3
来源
HMMT

题目详情

  1. [5] Alice, Bob, and Charlie each pick a 2-digit number at random. What is the probability that all of their numbers’ tens’ digits are different from each others’ tens’ digits and all of their numbers’ ones digits are different from each others’ ones’ digits?
解析
  1. [5] Alice, Bob, and Charlie each pick a 2-digit number at random. What is the probability that all of their numbers’ tens’ digits are different from each others’ tens’ digits and all of their numbers’ ones digits are different from each others’ ones’ digits? 9 8 8 7 112 Solution: = . 10 10 9 9 225