设总体 sim N(0,(1)^2),-|||-样本 ((X)_(1),(X)_(2),(X)_(3),(X)_(4))-|||-当 =[ ] =[ ] ]-|||-]-|||-=a(({X)_(1)+(X)_(2))}^2+b(({X)_(3)-3(X)_(4))}^2-|||-sim (chi )^2(n)-|||-=1