An instructor in an economics class is considering three different texts. She is also consid- ering three types of examinations multiple choice, essays, and a mix of multiple choice and essays. During the year she teaches nine sections of the course, and randomly assigns a text-examination type combination to each section. At the end of the course, she obtained students evaluations for each section. These ratings are shown in the accompany- ing table. EXAMINATION TEXT A B C Multiple choice 4.8 53 4.9 Essays 4.6 5.0 4.3 Mix 4.6 5.1 4.8

(a) Set out the analysis of variance table.

(b) Test the null hypothesis of equality of population mean ratings for the three texts.

(c) Test the null hypothesis of equality of population mean ratings for the three examina- tion types.