HMMT 二月 2001 · GEN2 赛 · 第 7 题
HMMT February 2001 — GEN2 Round — Problem 7
题目详情
- A real numbers x is randomly chosen in the interval − 15 , 15 . Find the probability 2 2 that the closest integer to x is odd.
解析
- A real numbers x is randomly chosen in the interval − 15 , 15 . Find the probability 2 2 that the closest integer to x is odd. [ ] 1 1 Solution: By using a graphical method, we can see that, for real x on − n − , n + , 2 2 n n an even integer, the probability that the closest integer to x is odd is . The desired 2 n +1 ( ) 15 probability is . 31