P(z=2)=P(X=0,y=2)+P(X=1y=1) +P(X=2,y=0) 424 -+-×一+— 49494936 P(Z=3)=P(X=1,y=2)+P(X=2,Y=1) 412 494936 P(Z=4)=P(X=2,y=2) 4936 Z的分布律为: 201234 pz 613124 3636363636P Z P X Y P X Y PX Y ( )( , )( , ) ( ,) = = = = + = = + == 2 0 2 11 2 0 =×+×+×= 1 4 4 9 2 4 4 9 1 4 1 9 13 36 PZ PX Y PX Y ( )( , )( , ) == = =+ = = 3 12 21 =×+×= 2 4 4 9 1 4 4 9 12 36 PZ PX Y ( )( , ) == = = 4 22 =×= 1 4 4 9 4 36 ∴ Z 的分布律为： Z 0 1 234 p Z 1 36 6 36 13 36 12 36 4 36