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Data Sufficiency ques - pls help

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achal46: Junior | Next Rank: 30 Posts; Posts: 10; Joined: Mon Jun 04, 2012 7:59 amFollowed by: 1 member; Thanked: 1 times

by achal46 » Mon Jul 09, 2012 2:10 am

George scored 85% on a test. Did George do better than 90% of his classmates on the test?

(1) The mean score on the test was 80%.
(2) The standard deviation was 2.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

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Source: Beat The GMAT — Problem Solving | Mon Jul 09, 2012 2:10 am

Jim@StratusPrep: MBA Admissions Consultant; Posts: 2279; Joined: Fri Nov 11, 2011 7:51 amFollowed by: 266 members; Location: New York; Thanked: 660 times; GMAT Score:770

by Jim@StratusPrep » Mon Jul 09, 2012 4:22 am

This is not something that is tested on the GMAT (as this is more a knowledge based question).

We would need both the mean and standard deviation for this (assuming normal distribution curve as well - which is likely the only thing that would be tested if this question were on the exam).

1) Insufficient, no standard deviation
2) insufficient, no mean

In a normal distribution we know that approximately 95 percent of the class performs lower than 2 distributions above the mean (First Year Stats will teach you this). This information would make the problem sufficient and the answer would be C.

However, you can argue that you do no know the shape of the curve and the answer would be E.

All in all, don't worry about this one...

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