Question: Course grades. Most students in a large statistics course are taught by teaching assistants (TAs). One section is taught by the course supervisor, a senior professor. The distribution of grades for the hundreds of students taught by TAs this semester was

The grades assigned by the professor to students in his section were

a) What percents of each grade did students in the professor’s section earn? In what ways does this distribution of grades differ from the TA distribution?

b) Because the TA distribution is based on hundreds of students, we are willing to regard it as a fixed probability distribution. If the professor’s grading follows this distribution, what are the expected counts of each grade in his section?

c) Does the chi-square test for goodness of fit give good evidence that the professor’s grades follow a different distribution? (State hypotheses, check the guidelines for using chi-square, give the test statistic and its P-value, and state your conclusion.)