The mean hourly wage for coal workers in the U。S. is $15.5 with a population standard deviation of $3.2. If the sample size is 30, the standard error of the sample mean is closest to:
选项:
A: 0.3413.
B: 0.1067.
C: 0.5842.
发布时间:2024-06-12 21:28:03