方差已知情况下总体均值的估计

• 当（成正态分布的）总体的均值μ和方差σ已知时，容量为n样本均值的分布随之确定，服从均值为μ、方差为σ2/n的正态分布。
• 根据样本方差均值的分布，可知：1.总体均值μ是样本均值的最佳点估计；2.置信度为1-α的置信区间可由相应z分数确定。

Estimation of population mean with known variance

• When the mean μ and variance σ of a normally distributed population are known, the distribution of sample mean with a capacity of n is determined, following a normal distribution of mean μ and variance σ2/n.
• According to the distribution of the mean variance of the sample, it can be concluded that: 1. The population mean μ is the best point estimate of the sample mean; The confidence interval with a confidence level of 1-α can be determined by the corresponding z-score.