what is the standard deviation of set S

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uptowngirl92: Master | Next Rank: 500 Posts; Posts: 447; Joined: Sun Apr 19, 2009 9:08 pm; Location: Kolkata,India; Thanked: 7 times; GMAT Score:670

by uptowngirl92 » Thu Jul 23, 2009 2:04 am

If set S consists of an odd number of even integers that have a normal distribution,what is the standard deviation of set S?
1. The mean of set S is 4
2.The median of set S is 4

Ok,so i have a silly querie:(
Each stmt. alone is insuff. and combining the two we know that only a set of consecutive integers will have mean=median.So (c).
However my concept is a bit wobbly.What about set {0,4,8}?
here mean=4=median.this satisfies the condition as the set {2,4,6}.

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Source: Beat The GMAT — Data Sufficiency | Thu Jul 23, 2009 2:04 am

Spaceman Spiff: Senior | Next Rank: 100 Posts; Posts: 54; Joined: Fri Apr 03, 2009 7:23 pm; Location: Los Angeles; Thanked: 1 times; GMAT Score:780

by Spaceman Spiff » Thu Jul 23, 2009 2:16 am

IMO E.

2,4,6 satisfies the condition and SD is 2
0,4,8 satisfies the condition and SD is 4

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Ian Stewart: GMAT Instructor; Posts: 2623; Joined: Mon Jun 02, 2008 3:17 amFollowed by: 355 members; Location: Montreal; Thanked: 1090 times; GMAT Score:780

by Ian Stewart » Thu Jul 23, 2009 2:59 am

The question doesn't make any sense. You can't possibly have a set which contains an odd number of even integers which has a 'normal distribution' (in technical terms which you certainly do *not* need to understand for the GMAT, the normal distribution is continuous and infinite, while a set of an odd number of integers is finite and discrete).

You do not need to know a single thing about normal distributions for the GMAT, so not only is this question deeply flawed, it's completely irrelevant to your test.

For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

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