(X1,X2,X3,X4,X5,X6)为来自总体X的简单随机样本所以(X1+X1+X3)~N(0,3)(X4+X5+X6)~N(0,3)所以而1/√3(X1+X1+X3)~N(0,1);1/√3(X4+X5+X6)~N(0,1)则[1/√3(X1+X1+X3)]^2+[1/√3(X4+X5+X6)]^2~X^2(2)也就是说c=1/3 cY~X^2(2)
