设随机变量的分布密度函数为,试求x的密度函数,数学期望和方差.F(X)...
设随机变量的分布密度函数为,试求x的密度函数,数学期望和方差.F(X)＝0,x＜-2,
x／4,-2≤x≤2,
1,x＞2
人气：466 ℃ 时间：2019-08-19 11:32:52
解答
先通过随机变量X的分布函数F(x)求导得到其概率密度函数f(x),再利用期望和二阶矩的定义式求出E(x)和E(x^2),进而得到方差
好好看看概率论的课本
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