The population mean is often written "x-bar." If you have a sample with n observations, it's the summation i = 1 to n of xi/n--that's the average.

人口均值经常写成“x-条形柱”，如果你有一个样本有n个观测者，是从 i=1到n和的xi/n，这是平均值。

youdao

If you have a sample with n observations, it's the summation I = 1 to n of xi/n--that's the average.

如果你有n个观测值,对Xi从i=1到n求和再除以n

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