A professor gives a multiple choice exam where each question has five choices. The professor decides not to count a question against students if the class as a whole does significantly worse on the question than they would have done simply by guessing. In other words, the teacher tests H_0: p=0.20H 0 :p=0.20H, start subscript, 0, end subscript, colon, p, equals, 0, point, 20 versus H_\text{a}: p<0.20H a :p<0.20H, start subscript, start text, a, end text, end subscript, colon, p, is less than, 0, point, 20 for each question, where ppp is the proportion of students who would correctly answer the question.