根据样本大小、均值、标准差和置信水平，计算样本均值的置信区间。
A confidence interval gives an estimated range of values which is likely to include an unknown population parameter. For example, instead of just saying the average height of men is 175cm, a 95% confidence interval might state that the true average height is somewhere between 173cm and 177cm. The confidence level (e.g., 95%) represents the long-term percentage of these calculated intervals that would contain the true value.