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GMat club test M11 doubt

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Senior Manager
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Joined: 12 Mar 2009
Posts: 301
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GMat club test M11 doubt [#permalink]

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New post 20 Jul 2009, 10:18
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

100% (00:04) correct 0% (00:00) wrong based on 12 sessions

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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.
The correct answer is E.


In case of E all the constants are different. Hence teh best option possible is 4 and not
5. Please explain.

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Re: GMat club test M11 doubt [#permalink]

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New post 20 Jul 2009, 16:48
1
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
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Re: GMat club test M11 doubt [#permalink]

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New post 21 Jul 2009, 03:06
Thanks GMATQuantCoach3, nicely explained, +1 Kudo

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If you would like to discuss this question please re-post it in the respective forum. Thank you!

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Re: GMat club test M11 doubt   [#permalink] 21 Jul 2009, 03:06
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