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# GMat club test M11 doubt

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Senior Manager
Joined: 12 Mar 2009
Posts: 318
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Kudos [?]: 106 [0], given: 1

GMat club test M11 doubt [#permalink]  20 Jul 2009, 09:18
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Difficulty:

(N/A)

Question Stats:

100% (01:08) correct 0% (00:00) wrong based on 0 sessions
Which of the following sets has the same standard deviation as set (a,b,c) ?
1. (ab,b^2,bc)
2. (2a, b+a, c+b)
3. (0 , b+a, c+b)
4. (ab,bc,ac)
5. (ab+c, a+ab, ab+b)

Explanation given:
The standard deviation of a set does not change when a constant is added to all the members of the set.

In case of E all the constants are different. Hence teh best option possible is 4 and not
Intern
Joined: 11 Jul 2009
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Re: GMat club test M11 doubt [#permalink]  20 Jul 2009, 15:48
1
KUDOS
If you rewrite set 5 as
(a+ab, b+ab, c+ab)

ab is the constant you're adding to a, b, and c.

Hope this clears things up.
Manager
Joined: 27 Jun 2008
Posts: 159
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Re: GMat club test M11 doubt [#permalink]  21 Jul 2009, 02:06
Thanks GMATQuantCoach3, nicely explained, +1 Kudo
Re: GMat club test M11 doubt   [#permalink] 21 Jul 2009, 02:06
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