Keith is helping to plan his school's end-of-year trip. So, he wants to ask a small sample of students about where they should go.
Pick all the ways of sampling the students that would produce a representative sample.
a: keith asks the 30 oldest students in his school he randomly picks which students to ask first
b: Keith uses a computer to randomly pick 30 students to ask
c Keith randomly chooses 10 students in each of the 3 grades then he asks those students
b: Keith uses a computer to randomly pick 30 students to ask
c: Keith randomly chooses 10 students in each of the 3 grades then he asks those students