PUMaC 2016 · 组合（B 组） · 第 2 题
PUMaC 2016 — Combinatorics (Division B) — Problem 2
题目详情
- Every day, Kaori flips a fair coin. She practices her violin if and only if the coin comes up heads. The probability that she practices at least five days this week can be written in simplest m form as . Compute m + n . n
解析
- The probability is ( ) ( ) ( ) 7 7 7
29 5 6 7 = , 7 2 128 so our answer is 29 + 128 = 157 . Problem written by Bill Huang.