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Set T consists of five integers: the first five odd prime numbers when

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Math Expert
Joined: 02 Sep 2009
Posts: 58402
Set T consists of five integers: the first five odd prime numbers when  [#permalink]

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16 Oct 2018, 01:07
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Difficulty:

55% (hard)

Question Stats:

43% (01:38) correct 57% (01:46) wrong based on 54 sessions

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Set T consists of five integers: the first five odd prime numbers when counting upward from zero. This gives set T a standard deviation of approximately 3.71. Which of the following values, if added to the set T, would increase the standard deviation of set T?

A. 11

B. 9

C. 7.8

D. 4.15

E. 3.7

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Joined: 17 May 2015
Posts: 247
Re: Set T consists of five integers: the first five odd prime numbers when  [#permalink]

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16 Oct 2018, 03:24
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Bunuel wrote:
Set T consists of five integers: the first five odd prime numbers when counting upward from zero. This gives set T a standard deviation of approximately 3.71. Which of the following values, if added to the set T, would increase the standard deviation of set T?

A. 11

B. 9

C. 7.8

D. 4.15

E. 3.7

Hi,

Set T consists of five integers: the first five odd prime numbers when counting upward from zero.

=> T = {3,5,7,11,13} , Mean = 39/5 = 7.8 , SD = 3.71 (given).

Any number within the range of Mean$$\pm$$ SD will not increase the SD of the new set.

i.e. Any number between 4.09 (7.8 - 3.71) and 11.51 (7.8 + 3.71) will not increase the SD of the new set.

Hence, the required number is 3.7. Answer (E).

Thanks.
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Joined: 14 Jun 2018
Posts: 218
Re: Set T consists of five integers: the first five odd prime numbers when  [#permalink]

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16 Oct 2018, 06:35
The further from the mean , the higher will be the change in standard deviation.
Ans E
Re: Set T consists of five integers: the first five odd prime numbers when   [#permalink] 16 Oct 2018, 06:35
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