2-23 某电压测量值服从正态分布,对该电压进行10次测量得被测电压的平均值 overrightarrow (U)=10.00W, 实验标-|||-准偏差 (U)=0.2V-|||-(1)求对应90%、95%、99%置信概率时平均值U的置信区间;-|||-(2)求平均值的置信区间为 overrightarrow (U)pm 1.50(overrightarrow (U)) overline (v)pm 2.5o(overline (v)) overrightarrow (U)pm 3.5Omega (overrightarrow (U)) 时的置信概率为多少?