HMMT 二月 2001 · GEN2 赛 · 第 7 题
HMMT February 2001 — GEN2 Round — Problem 7
题目详情
英文原题
- 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
英文解析
- 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 an even integer, the probability that the closest integer to x is odd is . The desiredn
2 n +1
( )
probability is .15
31