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Which of the following sets has the smallest standard deviation?

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Which of the following sets has the smallest standard deviation? [#permalink]

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Which of the following sets has the smallest standard deviation?

A. {2, 5, 13, 17, 23}
B. {3, 4, 7, 18, 18}
C. {1, 4, 12, 16, 17}
D. {-50, 2, 33, 34, 35}
E. {0, 0, 0, 19, 31}
[Reveal] Spoiler: OA

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Re: Which of the following sets has the smallest standard deviation? [#permalink]

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New post 29 Mar 2017, 10:05
Bunuel wrote:
Which of the following sets has the smallest standard deviation?

A. {2, 5, 13, 17, 23}
B. {3, 4, 7, 18, 18}
C. {1, 4, 12, 16, 17}
D. {-50, 2, 33, 34, 35}
E. {0, 0, 0, 19, 31}



Ans C

A,D &E are out since their ranges are high

B out ,as it has 2 extreme points from mean(ie 10)

Ans C
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Re: Which of the following sets has the smallest standard deviation? [#permalink]

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New post 29 Mar 2017, 12:03
rohit8865 Can you explain how B is out as it has 2 extreme points from mean
I understand why A, D and E are out.
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Re: Which of the following sets has the smallest standard deviation? [#permalink]

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New post 16 Jun 2017, 08:48
Refer this link
http://www.mathsisfun.com/data/standard ... #WhySquare
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Re: Which of the following sets has the smallest standard deviation? [#permalink]

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New post 06 Sep 2017, 12:20
Hi abhimahna,

Can you help me out here with this question? This needs a better explanation.
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Which of the following sets has the smallest standard deviation? [#permalink]

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New post 07 Sep 2017, 02:19
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TheMastermind wrote:
Hi abhimahna,

Can you help me out here with this question? This needs a better explanation.


Hi TheMastermind ,

Thanks for tagging me in this. I love this type of questions.

Here, you need to know one important concept.

Standard deviation is the amount of data that is farthest from the average of the numbers.

So, all you need to do is find out the average of each set and then determine the sum of the gaps of each numbers from the mean.

The lower the gap, the smaller the Standard Deviation.

Let me solve first 3 options for you. Rest I believe you can solve ( I didn't because I could see there will be big gaps.)

A. {2, 5, 13, 17, 23}

Mean = 12.

Difference of each term from this mean = 10, 7, 1,5,11.

Sum of these gaps/differences = 34.

B. {3, 4, 7, 18, 18}

Mean = 10.

Difference of each term from this mean = 7,6,3,8,8.

Sum of these gaps/differences = 32.

C. {1, 4, 12, 16, 17}

Mean = 10.

Difference of each term from this mean = 9, 6, 2, 6, 7.

Sum of these gaps/differences = 30.

Since C has the lowest GAP. C will have the lowest Standard Deviation. Hence, the answer.

Does that make sense?
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Which of the following sets has the smallest standard deviation?   [#permalink] 07 Sep 2017, 02:19
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