Chapter 7.6, Problem 27E

Grade Complaints Two of the mathematics professors at Enormous State University are Professor A (known for easy grading) and Professor F (known for tough grading). Last semester, roughly three quarters of Professor F’s class consisted of former students of Professor A; these students apparently felt encouraged by their (utterly undeserved) high grades. (Professor F’s own former students had fled in droves to Professor A’s class to try to shore up their grade-point averages.) At the end of the semester, as might have been predicted, all of Professor A’s former students wound up with a C– or lower. The rest of the students in the class— former students of Professor F who had decided to “stick it out”—fared better, and two thirds of them earned higher than a C–. After discovering what had befallen them, all the students who earned C– or lower got together and decided to send a delegation to the department chair to complain that their grade-point averages had been ruined by this callous and heartless beast! The contingent was to consist of 10 representatives selected at random from among them. How many of the 10 would you estimate to have been former students of Professor A?