A process characteristic has a true (population) mean of 150 and a true (propulation) standard deviation of 20. A sample of 25 item is taken from this process. The standard deviation of the sample is: A. 0.2 B. 0.8 C. 4.0 D. 5.0
某过程特性的真实(总体)均值150和真实(总体)标准差20,从这个过程中抽样25项,样品的标准差是: A. 0.2 B. 0.8 C. 4.0 D. 5.0 谁知道怎么求解,能列出详细过程最好,谢谢。