Here we have another inference question, so we don't have a conclusion with a well-structured line of reasoning. As always, make sure that you clearly understand the given information and pay attention to the details:
- Cheever College offers traditional classroom-based courses (CBCs) AND several online courses (OCs) via remote computer connection.
- According to a study, the average student grade for OCs was the same as the average student grade for CBCs.
- When calculating average grade for that study, course withdrawals were weighted as equivalent to a course failure.
- The rate of withdrawal was much lower for CBC students than for OC students.
OC students were more likely to withdraw. In the eyes of the study, those students who withdrew failed the course. So
before factoring in the students who did NOT withdraw, we are starting with a higher proportion of failure among the OC students. For example, if there were twice as many withdrawals from OCs as there were from CBCs, then we'd be starting with a failure rate that is twice as high among OC students as it is for CBC students (again, BEFORE factoring in the students who did not withdraw).
Now let's factor in the students who did NOT withdraw. Let's say that the average grade among OC students who did not withdraw was the SAME as the average grade among CBC students who did not withdraw. As stated above, there were more OC withdrawals. So if the
non-withdrawal averages are equal and there are
more OC withdrawals, then the
overall average of OC students would have to be
lower than the
overall average of CBC students.
But we are told that this is
not the case and that the overall averages are the same for both groups. Remember, when we are just looking at the withdrawals, we are starting with a higher failure proportion among OC students. In order for the average of the OC students to "catch-up" to the average of the CBC students, the average of the OC students who did NOT withdraw would have to be HIGHER than the average of the CBC students who did not withdraw. Otherwise, the CBC students would have a higher overall average.
Quote:
(A) Among students who did not withdraw, students enrolled in online courses got higher grades, on average, than students enrolled in classroom-based courses.
As described in the preceding analysis, choice (A) has to be true. Keep this one.
Quote:
(B) The number of students enrolled per course at the start of the school term is much higher, on average, for the online courses than for the classroom-based courses.
The study is concerned with AVERAGE grades, so we cannot determine anything about the actual
number of students per course. Eliminate (B).
Quote:
(C) There are no students who take both an online and a classroom-based course in the same school term.
The study compares average student grade for OCs to average student grade for CBCs. This study could be conducted even if some students took both types of courses. The study would simply include the student's OC grades in the OC average and include the student's CBC grades in the CBC average. So we might have students who took both types and we might not. (C) cannot be determined.
Quote:
(D) Among Cheever College students with the best grades, a significant majority take online, rather than classroom-based, courses.
As with choice (B), the findings involve AVERAGE grades. It is certainly possible that a large portion of the students with the BEST grades took CBCs. As long as the AVERAGE of OC students who did not withdraw was higher than the AVERAGE of the CBC students who did not withdraw, it doesn't matter which group has the students with the BEST grades. For example, it is possible that the 10
best students all took CBCs, the rest of the CBC students did poorly, and most of the OC students did fairly well.
Choice (D)
might be true, but we don't know for sure. And we certainly cannot determine that a
significant majority of the students with the best grades took OCs rather than CBCs. Eliminate (D).
Quote:
(E) Courses offered online tend to deal with subject matter that is less challenging than that of classroom-based courses.
The information in the passage does not offer any evidence to EXPLAIN the data. All we can determine is that the average of the OC students who did NOT withdraw has to be higher than the average of the CBC students who did not withdraw. A number of factors could explain this result (better teachers, better courses, etc). Choice (E) is a
possible explanation, but we cannot determine whether it is true based on the information in the passage. Eliminate (E).
Choice (A) is the only statement that HAS to be true.
_________________