CoreUI Logo CoreUI Logo
Question
新问题 返回

问题

概率统计 >> 概率论
Questions in category: 概率论 (Probability).

[Exer5-5] Exercise 41 of Book {Devore2017B} P.118

Posted by haifeng on 2020-03-23 20:59:38 last update 2020-03-23 21:12:50 | Answers (1) | 收藏

Suppose $E(X)=5$ and $E[X(X-1)]=27.5$. What is

  • $E(X^2)$ ? [Hint: $E[X(X-1)]=E[X^2-X]=E(X^2)-E(X)$.]
  • $V(X)$ ?
  • The general relationship among the quantities $E(X)$, $E[X(X-1)]$, and $V(X)$.