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diebeatsthegmat: Legendary Member; Posts: 1119; Joined: Fri May 07, 2010 8:50 amFollowed by: 3 members; Thanked: 29 times

by diebeatsthegmat » Fri May 06, 2011 11:22 am

Given a set {x, y, z}, if the first term in the data set above is 3, what is the third term?

(1) the range of this data set is 0

(2) the standard deviation of this data set is 0
i think the answer should be D.
statement 2 is obviously sufficient
statement 1: range=max-min=0 so max=min

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Source: Beat The GMAT — Data Sufficiency | Fri May 06, 2011 11:22 am

force5: Legendary Member; Posts: 582; Joined: Tue Mar 08, 2011 12:48 amFollowed by: 6 members; Thanked: 61 times; GMAT Score:740

by force5 » Fri May 06, 2011 12:13 pm

Seems like D for me too. i didn't understand what is your doubt?

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atulmangal: Legendary Member; Posts: 1112; Joined: Sat Feb 26, 2011 11:16 amFollowed by: 49 members; Thanked: 77 times

by atulmangal » Fri May 06, 2011 8:33 pm

Ans has to be Op D only

its a general principal if Range is zero that means all the no's are equal

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diebeatsthegmat: Legendary Member; Posts: 1119; Joined: Fri May 07, 2010 8:50 amFollowed by: 3 members; Thanked: 29 times

by diebeatsthegmat » Mon May 09, 2011 9:08 am

force5 wrote:Seems like D for me too. i didn't understand what is your doubt?

because in the page i read, the answer is not D. thats why i asked

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atulmangal: Legendary Member; Posts: 1112; Joined: Sat Feb 26, 2011 11:16 amFollowed by: 49 members; Thanked: 77 times

by atulmangal » Mon May 09, 2011 9:51 am

diebeatsthegmat wrote:
force5 wrote:Seems like D for me too. i didn't understand what is your doubt?
because in the page i read, the answer is not D. thats why i asked

So what's the ans given on that page???

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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 » Tue May 10, 2011 8:17 am

If the range is zero, the standard deviation is zero and vice versa; the two statements tell you the same thing. Further, if the range is zero, all the elements are equal, so the answer is certainly D.

The wording of the question is pretty awful. For one thing, sets are not ordered, so the question should not talk about the 'first element' or the 'third element' in the set (I don't know why it doesn't simply tell you that x=3 and ask for the value of z).

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

ianstewartgmat.com

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