11. Announcements. A high school in Wisconsin stopped having announcements read to students over the intercom system, choosing to have announcements displayed on television monitors located throughout the building. To see how students feel about the new system the principal wants to conduct a survey. Explain how to select a sample of about 500 students using each sampling method below: a. Simple random sample b. Stratified random sample with grade levels as strata c. Cluster sample with classrooms as clusters