
E(X)
【正确答案】:
P(X=0)=0.1+0.2+0.1=0.4;P(X=1)=0.2+0.2+0.2=0.6;E(X)=0×0.4+1×0.6=0.6
【题目解析】:
X的可能取值有两种:0、1P(X=0}=P{X=0,Y=0}+P{X=0,Y=1}+P{X=0,Y=2}=0.4P{X=1}=P{X=1,Y=0}+P{X=1,Y=1}+P{X=1,Y=2}=0.6
故E(X)=0×0.4+1×0.6=0.6

P(X=0)=0.1+0.2+0.1=0.4;P(X=1)=0.2+0.2+0.2=0.6;E(X)=0×0.4+1×0.6=0.6
X的可能取值有两种:0、1P(X=0}=P{X=0,Y=0}+P{X=0,Y=1}+P{X=0,Y=2}=0.4P{X=1}=P{X=1,Y=0}+P{X=1,Y=1}+P{X=1,Y=2}=0.6
故E(X)=0×0.4+1×0.6=0.6