For each scenario, identify the kind of sample used by the university administrators from Exercise 1:
a) Select several dormitories at random and contact everyone living in the selected dorms.
b) Using a computer-based list of registered students, contact 200 freshmen, 200 sophomores, 200 juniors, and 200 seniors selected at random from each class.
c) Using a computer-based alphabetical list of registered students, select one of the first 25 on the list by random and then contact the student whose name is 50 names later, and then every 50 names beyond that.