Each student in a certain sociology class is either an

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Each student in a certain sociology class is either an undergraduate student or a graduate student. What percentage of the students in the class are graduate students?
(1) The average score on the final exam for undergraduate students was 20 points lower than the average for all students in the class.
(2) The average score on the final exam for graduate students was 40 points higher than the average for all students in the class
Source: — Data Sufficiency |

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by puneetkhurana2000 » Sun Dec 16, 2012 3:36 pm
Statement 1) No information about the average of graduate students. So Not Sufficient!!!

Statement 2) No information about the average of undergraduate students. So Not Sufficient!!!

Together we have Ratio of Undergraduate to Graduate Students = ((40 + x) - x )/(x - (x - 20)) = 2/1 ...x here represents the total average of the class.

So 33.33% of total students are graduates.

Sufficient Together!!!

Answer C.