4.(1)设样本x1,x2,···,X6来自总体N(0,1), =(({X)_(1)+(X)_(2)+(X)_(3))}^2+((X)_(4)+-|||-_(5)+({x)_(6)}^2, 试确定常数C使CY 服从x^2分布.-|||-(2)设样本X1,X2,···X5来自总体N(0,1), =dfrac (C({X)_(1)+(X)_(2))}({({{X)_(3)}^2+({X)_(4)}^2+({X)_(5)}^2)}^1/2}, 试确-|||-定常数C使Y服从t分布.-|||-(3)已知总体 approx t(n), 求证 ^2approx F(1,n),