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