In Table 6.1 and Example 6.1, we considered samples of n = 4 observations from a popa- lation of N 6 values of years on the job for employees. The population mean is -5.5 years.

(a) Confirm from the six population values that the population variance is

(b) Confirm, following the approach of Example 6.1, that the variance of the sampling distribution of the sample mean is 47 =(xx) (x) = 120

(c) Verify for this example that N-n 17 N-1