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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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Joined: 19 Mar 2014
Posts: 942
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Concentration: Finance, Entrepreneurship
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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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Updated on: 28 Oct 2017, 00:15
1
00:00

Difficulty:

35% (medium)

Question Stats:

70% (01:17) correct 30% (01:22) wrong based on 83 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

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Best AWA Template: https://gmatclub.com/forum/how-to-get-6-0-awa-my-guide-64327.html#p470475

Originally posted by ydmuley on 27 Oct 2017, 19:41.
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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Joined: 25 Feb 2013
Posts: 1217
Location: India
GPA: 3.82
Re: If the mean of list A is 6.8 and the standard deviation is 3.6, then  [#permalink]

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Updated on: 27 Oct 2017, 21:23
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

Originally posted by niks18 on 27 Oct 2017, 20:08.
Last edited by niks18 on 27 Oct 2017, 21:23, edited 1 time in total.
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WE: Engineering (Health Care)
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
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
Intern
Joined: 04 Oct 2017
Posts: 9
Concentration: Finance, Operations
WE: Engineering (Consulting)
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

Posted from my mobile device
Math Expert
Joined: 02 Aug 2009
Posts: 7106
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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3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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