问题如下：
Given a discrete uniform distribution, the possible outcome includes 25 integers from 1 to 25, which of the following is the corrcet value of P( 5 ≤ X < 10 ) ?
选项：
A.0.04.
B.0.20.
C.0.50.
解释：
B is correct. The possible outcome includes 25 integers, each integer has a probability of 0.04. P(5 ≤ X < 10) = P(5) + P(6) + P(7) + P(8) + P(9) = 0.04×5 = 0.20.
老师我的解题思路是1/25=0.04，然后把p6，p7，p8，p9先算了combination算出阶层然后乘以binomial 公式，把这5个结果相加，能麻烦老师帮我分析下我的思路是错在哪里吗？
