In taking a sample of n observations from a population of N members, the variance of the sampling distribution of the sample means is as follows:

They quantity (N - n) / (N - 1) is called the finite population correction factor.
a. To get some feeling for possible magnitudes of the finite population correction factor, calculate it for samples of n = 20 observations from populations of members: 20, 40, 100, 1,000, 10,000.
b. Explain why the result found in part a, is precisely what one should expect on intuitive grounds.
c. Given the results in part a, discuss the practical significance of using the finite-population correction factor for samples of 20 observations from populations of different sizes.

-- n N 1