Determine the type of sampling (random, stratified, systematic,
cluster, convenience) being conducted in the following situations.
a. On election day, a pollster for XYZ News positions herself outside a polling place near her office. She then asks the first 50 voters leaving the polling place to complete a survey.
b. An internet service provider randomly selects 15 residential blocks from a large city. It then surveys every household in these 15 blocks to determine the number that would upgrade to higher speed service, if it were available.
c. At a high school there are 574 sophomores, 562 juniors, and 532 seniors. The principal randomly selects 30 students from each group (sophomores, juniors, and seniors) to take a survey on the cafeteria’s food.
d. Officials for the PA Turnpike Commission offer a survey to every 50th vehicle passing through a toll facility.