152****10442022-10-31 18:38:57
152****1044A discrete random variable is characterized by the probability mass function (pmf) as given by f(x) = x*a, and its domain is the set of integers {6, 7, 8., 9, and 10}. What is the variable's expected value? A 6.67 B 8.00 C 8.25 D 9.33
查看试题回答（1）
最佳
Crystal2022-10-31 21:18:58
Crystal你为什么要对a做平方。
- 评论（0）
- 追问（2）
- 追问
-
We know that 6a + 7a + 8a + 9a + 10a = 1.0 such that a = 1/40 =0.0250 and the pmf is given by f(x) = x/40 = 0.0250*x. The expected value equals 1/40*(6^2 +7^2 + 8^2 + 9^2 + 10^2) = 8.25 这个答案看不懂 这个是算变量得均值对吗？为什么答案里变量都要平方？
- 追答
-
ax表示的是概率，概率乘以随机变量x然后求和才表示的是均值的概念。
评论
0/1000
追答
0/1000
+上传图片