Dr Myers, Mr. Murray and Mr. Tremblay have always maintained that they give the same proportion of A grades in their statistics courses. An enterprising student wishes to test this assertion and proceeds to take a random sample of former statistics students. The results are shown below:
Professor Dr. Myers Mr. Murray Mr. Tremblay
A Grades 30 22 18
Non A Grades 170 78 82
At an alpha level of 0.01 test the contention that the proportion of A grades are the same for the three professors.