This section presented Formulas 6-5 and 6-6, which are used for determining sample size. In both cases we assumed that the population is infinite or very large, or that we are sampling with replacement. When we have a relatively small population with size N and sample without replacement, we modify £ to include the finite population correction factor shown here, and we can solve for n to obtain the result shown to the right. Use this result to repeat Exercise 21, assuming that we limit our population to a town of 5000 people.

Npalz palz + (N - 1)E pq N -n n VN-1