More sampling:Use the following sampling methods to describe the type of sampling represented in the following problems.

a. Simple Random Sample d. Systematic

b. Stratified e. Convenience

c. Cluster

19. Before premiering a blockbuster movie at a theater, test screenings are done beforehand.Each theater premiering the movie is supposed to interview every 20th person as they leave the theater when the movie over.Identify the type of sampling used in this example.

20. A biology teacher wants to know how the students in her department feel about a certain course sequence.She takes a list of students in her department in which the students are numbered as they are listed in alphabetical order.She uses a random number generator to select 40 numbers and interviews the students that those numbers represent in the alphabetical listing.Identify the type of sampling used in this example.

21. The cafeteria decides to change their menu selection.To determine possible new menu items they interview every 10^th student that checks out of the cafeteria line on a given day.Identify the type of sampling used in this example.