The members of a population have been numbered 1–50. A sample of size 20 is to be taken from the population, using cluster sampling. The clusters are of equal size 10, where cluster #1 consists of the members of the population numbered 1–10, cluster #2 consists of the members of the population numbered 11–20, and so forth.

a. Apply Procedure 1.2 on page 18 to determine the sample (i.e., the numbers corresponding to the members of the population that are included in the sample). 

b. Suppose that, in Step 2 of Procedure 1.2, clusters #1 and #3 are selected. Determine the sample.