(a) The organizers of a conference want to survey attendees about the registration fee. Which of the following best describes a systematic sampleof attendees?

• The organizers take a list of the attendees and select every6th attendees until60 attendees are selected.
• The organizers form groups of12attendees based on the day the attendees registered. Then, the organizers randomly choose5 groups and select all of the attendees in these groups.
• The organizers select the first60 attendees who register for the conference because these attendees are easily accessible.

(b) Counselors at a college want to poll students about how much time the students spend studying. Which of the following best describes arandom sampleof students?

• The counselors take a list of the students and select every4th student until64students are selected.
• The students living in a particular dorm building on campus are easily accessible. So, the counselors select the64 students living in that particular dorm building.
• The counselors use a computer program to draw64 students at random and select these students. Every set of64 students is equally likely to be drawn by the computer program.

(c) A facilities supervisor at a sports stadium wants to rate the condition of the seats at the stadium. Which of the following best describes acluster sampleof seats?

• The supervisor uses a computer program to draw50 seats at random and selects these seats. Every set of50 seats is equally likely to be drawn by the computer program.
• The supervisor forms groups of10 seats based on the sections the seats are in. Then, she selects all of the seats in5 randomly chosen groups.
• The supervisor forms2 groups of seats based on the dates the seats were last replaced. Then, she selects25seats at random from each group.