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# Which of the following choices lists the four datasets above in order

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Math Expert
Joined: 02 Sep 2009
Posts: 51281
Which of the following choices lists the four datasets above in order  [#permalink]

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30 Jul 2018, 23:04
00:00

Difficulty:

15% (low)

Question Stats:

88% (00:52) correct 13% (00:49) wrong based on 48 sessions

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Dataset W: –9, –3, 3, 9
Dataset X: 2, 4, 6, 8
Dataset Y: 100, 101, 102, 103
Dataset Z: 7, 7, 7, 7

Which of the following choices lists the four datasets above in order from least standard deviation to greatest standard deviation?

(A) Z, W, X, Y,
(B) Z, W, Y, X
(C) Z, Y, W, X
(D) Z, Y, X, W
(E) Z, X, Y, W

_________________
Math Expert
Joined: 02 Aug 2009
Posts: 7112
Which of the following choices lists the four datasets above in order  [#permalink]

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31 Jul 2018, 00:32
Bunuel wrote:
Dataset W: –9, –3, 3, 9
Dataset X: 2, 4, 6, 8
Dataset Y: 100, 101, 102, 103
Dataset Z: 7, 7, 7, 7

Which of the following choices lists the four datasets above in order from least standard deviation to greatest standard deviation?

(A) Z, W, X, Y,
(B) Z, W, Y, X
(C) Z, Y, W, X
(D) Z, Y, X, W
(E) Z, X, Y, W

Standard deviation is the SPREAD of each element from average..
greater the spread more the SD, lesser the spread, smaller the SD

Dataset W: –9, –3, 3, 9...........................Biggest spread, largest SD
Dataset X: 2, 4, 6, 8................................range is 6, so SD<W
Dataset Y: 100, 101, 102, 103...................Range is just 3, so SD is >z but < than X and Y
Dataset Z: 7, 7, 7, 7................................ No spread so SD is 0
Also are in AP..
Z has 0 difference, Y has 1, X has 2 and W has 6

sequence in ascending order = Z, Y, X, W

D
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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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Which of the following choices lists the four datasets above in order &nbs [#permalink] 31 Jul 2018, 00:32
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