Question

概率论习题求助

设离散型随机变量X的分布函数为F(X)=
0 x<-2,
0.1 -2<=x<0,
0.4 0<=x<1,
0.8 1<=x<3,
1 x>=3
求E(X),E(1-2X)

Answer 1

P(X=-2)=0.1;
P(X=0)=0.3;
P(X=1)=0.4;
P(X=3)=0.2;
E(X)=-2*0.1+0*0.3+1*0.4+3*0.2=0.8;

E(1-2X)=1-2E(X)=1-1.6=-0.6;