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# Set X consists of 8 integers. Is the standard deviation of

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Senior Manager
Joined: 19 Mar 2008
Posts: 258
Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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Updated on: 07 Sep 2014, 06:50
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61% (00:57) correct 39% (01:10) wrong based on 268 sessions

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Set X consists of 8 integers. Is the standard deviation of set X equal to zero?

(1) The range of set X is equal to 3

(2) The mean of set X is equal to 5

Originally posted by judokan on 25 Jul 2008, 23:42.
Last edited by Bunuel on 07 Sep 2014, 06:50, edited 1 time in total.
Edited the question and added the OA.
Director
Joined: 10 Sep 2007
Posts: 613
Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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26 Jul 2008, 07:56
IMO A.

1) Range 3 implies there is at least 2 different elements in set, so std. deviation cannot be zero.

2) Median 5 does not tells us whether all the elements in set is same or different. Thereby, nothing can be said. E.g {5,5,5,5,5} with std 0 and {1,5,9} std not equal to 0.
Intern
Joined: 07 Jan 2008
Posts: 47
Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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08 Nov 2008, 18:00
I agree with A, but i have a different reasoning. pls let me know if i'm wrong

{ 2,5,3,9} Range is 2-9

The range of set X is equal to 3
Wouldnt that mean all the elements are 3 in set X
Director
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Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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12 Nov 2008, 10:50
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sumanamba wrote:
I agree with A, but i have a different reasoning. pls let me know if i'm wrong

{ 2,5,3,9} Range is 2-9

The range of set X is equal to 3
Wouldnt that mean all the elements are 3 in set X

Your question is correct, however, your reasoning is flawed on following account.
1) Range of { 2,5,3,9} is 9-2 = 7 and not 3.
2) Range is maximum value subtracted from minimum value in the set. If all the elements in a set are equal then range will be zero.
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Joined: 07 Apr 2014
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Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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07 Sep 2014, 00:27
1
judokan wrote:
Set X consists of 8 integers. Is the standard deviation of set X equal to zero?

(1) The range of set X is equal to 3

(2) The mean of set X is equal to 5

1. when the range is not zero then SD too. Suff

2. Mean = 5 for 8 terms but not sure if all terms are same or different so Not suff.
Manager
Joined: 29 Jul 2018
Posts: 100
Concentration: Finance, Statistics
GMAT 1: 620 Q45 V31
Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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03 Oct 2018, 01:41
for sd to be zero range should be 0
{5,5,5,5}
range 0
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Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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24 Nov 2019, 11:06
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Re: Set X consists of 8 integers. Is the standard deviation of   [#permalink] 24 Nov 2019, 11:06