请问这几个概率怎么求

Question

Answer 1

应该是这样子：P(X2=1)=1/2
p(X2=1|Y=0)=p(x2=1&Y=0)/p(Y=0)=
{1/8*(2/3+5/9+1/5+1/6)} / {1/8*(1+5/6+2/3+3/10+5/9+1/4+1/5+1/6)}=(2/3+5/9+1/5+1/6) / (1+5/6+2/3+3/10+5/9+1/4+1/5+1/6)
P(A|B)=P(AB)/P(B)