9. Teacher Ratings: Grades Professor Stone complains that students’ teacher ratings depend on the grade students receive. In other words, according to Professor Stone, a teacher who gives good grades gets good ratings, and a teacher who gives bad grades gets bad ratings. To test this claim, the Student Assembly took a random sample of 300 teacher ratings on which the students’

grades for the course also were indicated. The results are given in the following table. Test the hypothesis that teacher ratings and student grades are independent at the 0.01 level of significance.

Rating A B C F (or withdrawal) Row Total Excellent 14 18 15 3 50 Average 25 35 75 15 150 Poor 21 27 40 12 100 Column Total 60 80 130 30 300