Question

一道概率题目（倒数第二题）麻烦高手指点.）

Answer 1

根据联合分布：

YX -1 0 1 pj

0 5/20 2/20 6/20 13/20

1 3/20 3/20 1/20 7/20

pi 8/20 5/20 7/20

E(xy)=-1*3/20+1*1/20=-1/10

D(X)=E(X^2)-E(X)^2=1*(8/20+7/20)-(-1/20)^2=299/400

D(Y)=E(Y^2)-E(Y)^2=1*7/20-(7/20)^2=91/400

pxy =[E(xy)-E(x)E(y)]/√(D(X)*D(Y))=

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