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# If the mean of list A is 6.8 and the standard deviation is 3.6, then

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If the mean of list A is 6.8 and the standard deviation is 3.6, then [#permalink]

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27 Oct 2017, 19:41
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35% (medium)

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66% (00:47) correct 34% (00:48) wrong based on 47 sessions

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If the mean of list A is 6.8 and the standard deviation is 3.6, then how many elements of list A are within 1 unit of standard deviation of the mean?

A = {2, 9, 2, 6, 9, 10, 7, 4, 5, 14}

A. 3
B. 4
C. 5
D. 6
E. 7
[Reveal] Spoiler: OA

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Last edited by Bunuel on 28 Oct 2017, 00:15, edited 1 time in total.
Merged topic and moved to PS forum.

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Re: If the mean of list A is 6.8 and the standard deviation is 3.6, then [#permalink]

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27 Oct 2017, 20:08
ydmuley wrote:
If the mean of list A is 6.8 and the standard deviation is 3.6, then how many elements of list A are within 1 unit of standard deviation of the mean?

A = {2, 9, 2, 6, 9, 10, 7, 4, 5, 14}

A. 3
B. 4
C. 5
D. 6
E. 7

No of elements within 1 st. deviation from mean are in the range

$$(6.8−3.6)$$ and $$(6.8+3.6)$$ i.e 1 st. deviation to the left of mean and 1 st. deviation to the right of mean

so no of elements in the range $$3.2$$ to $$10.4=$$ {4,5,6,7,9,9,10} $$=7$$

Option E

Last edited by niks18 on 27 Oct 2017, 21:23, edited 1 time in total.

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Re: If the mean of list A is 6.8 and the standard deviation is 3.6, then [#permalink]

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27 Oct 2017, 20:31
1
KUDOS
ydmuley wrote:
If the mean of list A is 6.8 and the standard deviation is 3.6, then how many elements of list A are within 1 unit of standard deviation of the mean?

A = {2, 9, 2, 6, 9, 10, 7, 4, 5, 14}

A. 3
B. 4
C. 5
D. 6
E. 7

For example,
if IQ has an average of 50 and a standard deviation of 10,
and you have an IQ of 70,
then you are 2 standard deviations above the average

So this question is asked in (6.8-3.6) <= element < (6.8 + 3.6), how many of these elements are

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Re: If the mean of list A is 6.8 and the standard deviation is 3.6, then [#permalink]

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27 Oct 2017, 20:56
Option E for me : the required nos should be within
6.8- 3.6 to 6.8+3.6
Thus seven nos out of the total nos given.

Saba

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Re: If the mean of list A is 6.8 and the standard deviation is 3.6, then [#permalink]

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27 Oct 2017, 21:17
ydmuley wrote:
If the mean of list A is 6.8 and the standard deviation is 3.6, then how many elements of list A are within 1 unit of standard deviation of the mean?

A = {2, 9, 2, 6, 9, 10, 7, 4, 5, 14}

A. 3
B. 4
C. 5
D. 6
E. 7

Pl post it in correct forum that is PS and not DS.
Also it is not 700 level Q, involves straight calculations.
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Kudos [?]: 6115 [0], given: 121

Re: If the mean of list A is 6.8 and the standard deviation is 3.6, then   [#permalink] 27 Oct 2017, 21:17
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