a)
marginal distribution of X: f(x)= = =(4x+6)/42=(2x+3)/21 for x=1,2,3
b)
marginal distribution of Y: f(y)= = =(6+3y)/42=(y+2)/14 for y=0,1,2,3
3 a)
E(XY)= =(0*1*(0+1)/42+0*2*(0+2)/42+...+3*3*(3+3)/42) =4.000
b)
E(X)= =1*(2*1+3)/21+2*(2*2+3)/21+3*(2*3+3)/21 =46/21
c)E(Y)= =1*(1+2)/14+2*(2+2)/14+3*(3+2)/14=13/7
d)
Cov(X,Y)=E(XY)-E(X)*E(Y)=-0.068
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