9.设总体服从正态分布N(μ,1),且μ未知,设-|||-X1,X2,···,Xn为来自该总体的一个样本,记-|||-overline (X)=dfrac (1)(n)sum _(i=1)^n(X)_(i)(S)^2=dfrac (1)(n-1)sum _(i=1)^n(({X)_(i)-overline (X))}^2 则^H的置信水平-|||-为 1-a 的置信区间公式是-|||-A (overline (X)-(z)_(dfrac {alpha )(2)}sqrt (n),X+(z)_(dfrac {alpha )(2)}+dfrac (1)(sqrt {n)})-|||-B (overline (X)-(t)_(dfrac {a)(2)}(n-1)dfrac (1)(sqrt {n)},overline (X)+(t)_(dfrac {a)(2)}(n-1)dfrac (1)(sqrt {n)}-|||-C (overline (X)-(t)_(dfrac {a)(2)}(n-1)dfrac (S)(sqrt {n)},overline (X)+(t)_(dfrac {a)(2)}(n-1)dfrac (S)(sqrt {n)}-|||-D (overline (X)-(z)_(dfrac {alpha )(2)}dfrac (s)(sqrt {n)},overline (X)+(z)_(dfrac {alpha )(2)}dfrac (s)(sqrt {n)})