(1)在没有取白球的情况下取了一次红球,利用压缩样本空间则相当于只有1个红球,2个黑球放回摸两次,其中摸了一个红球
∴P(X=1|Z=0)=
=
*2
C
*
C
C
4 9
(2)X,Y取值范围为0,1,2,故
P(X=1|Z=0)=
=
*2
C
*
C
C
P(X=0,Y=0)=4 9
=
*
C
C
*
C
C
1 4
P(X=1,Y=0)=
=
*
C
C
*
C
C
1 6
P(X=2,Y=0)=
=1
*
C
C
1 36
P(X=0,Y=1)=
=
*
C
*
C
C
*
C
C
1 3
P(X=1,Y=1)=
=
*
C
C
*
C
C
1 9
P(X=2,Y=1)=0
P(X=0,Y=2)=
=
*
C
C
*
C
C
1 9
P(X=1,Y=2)=0
P(X=2,Y=2)=0