[問題] 機率一問

[goshagainfuc (...)]

l. let X be a random variable of the discrete type with pmf p(x) that is
   positive on the nennegative integers and is equal to zero elsewhere.
   show that
                     ∞
               E(X)= Σ [1-F(x)]
                     x=0
   where F(x) is the cdf of X

(幫忙一下吧前面一題是連續的我有算出來但這題離散的就湊不出答案了@@")

2. let X be a random variable with a pdf f(x) and mgf M(t). Suppose f is
   symmetric about 0, ( f(-x)=f(x) ). show that

                M(-t)=M(t)

(也是湊不出答案@@")

--
※ 發信站: 批踢踢實業坊(ptt.cc) 
◆ From: 218.167.73.130