已知随机变量\(ξ\)的取值为不大于\(n\)的非负整数值,它的分布列为:
\(ξ\) | \(0\) | \(1\) | \(2\) | \(…\) | \(n\) |
\(P\) | \(p_{0}\) | \(p_{1}\) | \(p_{2}\) | \(…\) | \(p_{n}\) |
其中\(p_{i}(i=0,1,2,…,n)\)满足:\(p_{i}∈[0,1]\),且\(p_{0}+p_{1}+p_{2}+…+p_{n}=1\).
定义由\(ξ\)生成的函数\(f(x)=p_{0}+p_{1}x+p_{2}x^{2}+…+p_{n}x^{n}\),令\(g(x)=f′(x)\).
\((I)\)若由\(ξ\)生成的函数\(f(x)= \dfrac {1}{4}x+ \dfrac {1}{2}x^{2}+ \dfrac {1}{4}x^{3}\),求\(P(ξ=2)\)的值;
\((II)\)求证:随机变量\(ξ\)的数学期望\(E(ξ)=g(1)\),\(ξ\)的方差\(D(ξ)=g′(1)+g(1)-(g(1))^{2}\);\((D(ξ)= \sum\limits_{i=0}^{n}(i-E(ξ))^{2}⋅p_{i})\)
\((\)Ⅲ\()\)现投掷一枚骰子两次,随机变量\(ξ\)表示两次掷出的点数之和,此时由\(ξ\)生成的函数记为\(h(x)\),求\(h(2)\)的值.