A professor wanted to determine whether an online homework system improved scores on a final exam. In the fall​ semester, he taught a class using the online homework system​ (which meant students did their homework online and received instant feedback about their answers along with helpful​ guidance). In the spring​ semester, he taught a class without the homework system​ (which meant students were responsible for doing their homework the​ old-fashioned way dash– paper and​ pencil). The professor made sure to teach the two courses identically​ (same text,​ syllabus, tests, meeting​ time, meeting​ location, and so​ on). The table summarizes the results of the two classes on their final exam. Complete parts ​(a) through ​(e) .