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

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Senior Manager
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Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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New post Updated on: 07 Sep 2014, 07:50
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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 26 Jul 2008, 00:42.
Last edited by Bunuel on 07 Sep 2014, 07:50, edited 1 time in total.
Edited the question and added the OA.
Director
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Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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New post 26 Jul 2008, 08:56
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.
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Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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New post 08 Nov 2008, 19:00
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
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Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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New post 12 Nov 2008, 11:50
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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Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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New post 07 Sep 2014, 01:27
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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. :twisted: Suff

2. Mean = 5 for 8 terms but not sure if all terms are same or different so Not suff.
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Re: Set X consists of 8 integers. Is the standard deviation of  [#permalink]

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New post 03 Oct 2018, 02:41
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] 03 Oct 2018, 02:41
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