KaranB1 wrote:
A survey recently conducted at the Global Business School has thrown up two interesting findings.
Finding 1: In the last ten years, students attending Professor James’ Economics classes were more likely to score in the top 10% of the class than were other students
Finding 2: In the last ten years, most of the students who scored in the top 10% of the class did not take classes from Professor James.
If the statements above are true, which of the following must be true?
A) The quality of classes conducted by Professor James has probably decreased
B) The number of students not taking classes from Professor James has increased over the last ten years
C) There must be some factor other than attending Professor James’ classes that can also make a student perform well in the subject
D) The overall quality of the students who have joined Global Business School in the last ten years has increased
E) Professor James needs to change his teaching methods if he wants more students to attend his classes
The first thing to do is to establish how the two findings co-exist.
Say there are10 professors with 100 students each. So 10% of total 1000 students would be the top 100 students.
Say 20% of James' students make it to top 100 i.e. 20 of his students.
Of the other 9 professors, the students have a lower probability of making to top 100.
But of the top 100, 20 students are James' and 80 students are non-James'. So most of the top 10% did not come from James.
So there is something else that makes students successful (the 80 students who are not from James' class)
A) The quality of classes conducted by Professor James has probably decreased
Note that we have no data comparing 10 years back to today. So anything that says "this decreased over 10 yrs" or "that increased over 10 yrs" is not correct. We are only talking about the 10 year data - what has been happening for the last 10 years. Not what increased/decreased 10 yrs ago to now.
B) The number of students not taking classes from Professor James has increased over the last ten years
Same logic as (A)
C) There must be some factor other than attending Professor James’ classes that can also make a student perform well in the subject
Correct. The 80 students did succeed without James' class.
D) The overall quality of the students who have joined Global Business School in the last ten years has increased
Same logic as (A)
E) Professor James needs to change his teaching methods if he wants more students to attend his classes
This is a conjecture. What he needs to do to make more people attend his classes is beyond the scope of the argument.
Answer (C)
_________________
Karishma
Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >