A high school has grades 9 through 12 in equal proportions. The principal says that he chose 40 students at random to participate in a survey and chose 18 seniors, 11 juniors, 7 sophomores and 4 freshmen. Is there evidence that the principal did not choose the students at random?

Question

anonymous · Answer

he didnt choose the same amount of students from each grade level

anonymous · Answer

How did you figure out the answer?

studygurl14 · Answer

Grades 9 through 12, meaning 4 grades. That means that the probability of the principal picking a student in 9th is 1/4, in 10th the prob is 1/4, and that same for 11th and 12th. This proves he didn't choose randomly because he picked 40 students, meaning he should have gotten approximately 10 students from each grade lv.