如果答案是这样的话基本思路如下:
P{X=0,Y=0}=1/3*1/3*1/3*A(0,3)=1/27
P{X=0,Y=1}=1/3*1/3*1/3*A(1,3)=3/27
P{X=0,Y=2}=1/3*1/3*1/3*A(1,3)=3/27
P{X=0,Y=3}=1/3*1/3*1/3*A(0,3)=1/27
P{X=1,Y=0}=1/3*1/3*1/3*A(1,3)=3/27
P{X=1,Y=1}=1/3*1/3*1/3*A(3,3)=6/27
P{X=1,Y=2}=1/3*1/3*1/3*A(1,3)=3/27
P{X=2,Y=0}=1/3*1/3*1/3*A(1,3)=3/27
P{X=2,Y=1}=1/3*1/3*1/3*A(1,3)=3/27
P{X=3,Y=0}=1/3*1/3*1/3*A(0,3)=1/27
[ 本帖最后由 x851109 于 2007-12-20 22:18 编辑 ] |