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# Mean score of a class -9

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Director
Status: Finally Done. Admitted in Kellogg for 2015 intake
Joined: 25 Jun 2011
Posts: 563
Location: United Kingdom
GMAT 1: 730 Q49 V40
GPA: 2.9
WE: Information Technology (Consulting)
Followers: 21

Kudos [?]: 999 [0], given: 217

Mean score of a class -9 [#permalink]  23 Nov 2011, 13:03
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Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 2 sessions
The mean score of a class on a test was 60 and the standard deviation was 15. If Elena's score was within 2 standard deviations of the mean, what is the lowest score she could have received?

Again - what's the meaning of 2 SD's from the mean?
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Best Regards,
E.

MGMAT 1 --> 530
MGMAT 2--> 640
MGMAT 3 ---> 610
GMAT ==> 730

Senior Manager
Status: D-Day is on February 10th. and I am not stressed
Affiliations: American Management association, American Association of financial accountants
Joined: 12 Apr 2011
Posts: 277
Location: Kuwait
Schools: Columbia university
Followers: 4

Kudos [?]: 95 [0], given: 52

Re: Mean score of a class -9 [#permalink]  23 Nov 2011, 13:56
1 SD from the mean is ADDING and Subtrating the amount if standard deviation from the mean one time. 2 SD from the mean is ADDING and Subtracting TWICE.

for example in this question..

1SD from the mean ranges from 75 to 45, where 75 is within SD above the mean and 45 within 1SD below the mean

2SD=15 TWICE=30 from the the mean, which is 90 to 30, where 90 is within 2 SD above the mean AND 30 is within 2 SD below the mean.

hope this is clear enough, feel free to ask further questions
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Joined: 07 Nov 2011
Posts: 31
Followers: 0

Kudos [?]: 0 [0], given: 9

Re: Mean score of a class -9 [#permalink]  23 Nov 2011, 20:19
manalq8 wrote:
1 SD from the mean is ADDING and Subtrating the amount if standard deviation from the mean one time. 2 SD from the mean is ADDING and Subtracting TWICE.

for example in this question..

1SD from the mean ranges from 75 to 45, where 75 is within SD above the mean and 45 within 1SD below the mean

2SD=15 TWICE=30 from the the mean, which is 90 to 30, where 90 is within 2 SD above the mean AND 30 is within 2 SD below the mean.

hope this is clear enough, feel free to ask further questions

i have a serious doubt on the reasoning for 2SD and 1SD ...is the explanation right ...Anyone pls help...
Re: Mean score of a class -9   [#permalink] 23 Nov 2011, 20:19
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