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# The class mean score on a test was 60, and the standard deviation was

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The class mean score on a test was 60, and the standard deviation was [#permalink]

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23 Nov 2011, 14:03
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Difficulty:

35% (medium)

Question Stats:

59% (00:23) correct 41% (00:32) wrong based on 243 sessions

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The class mean score on a test was 60, and the standard deviation was 15. If Jack's score was within 2 standard deviations of the mean, what is the lowest score he could have received?

(A) 30
(B) 31
(C) 45
(D) 90
(E) 89
[Reveal] Spoiler: OA

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Last edited by Bunuel on 06 May 2015, 02:05, edited 1 time in total.
Renamed the topic, edited the question and added the OA.

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Re: The class mean score on a test was 60, and the standard deviation was [#permalink]

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23 Nov 2011, 14:56
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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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Re: The class mean score on a test was 60, and the standard deviation was [#permalink]

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23 Nov 2011, 21:19
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...

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Re: The class mean score on a test was 60, and the standard deviation was [#permalink]

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06 May 2015, 00:47
only when you get 50/51, standard deviation question appears. if you get 49, there would be no that question. do not worry of this kind of question if you need only 49

gmat is very basic
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Kudos [?]: 167 [0], given: 916

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Re: The class mean score on a test was 60, and the standard deviation was [#permalink]

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06 May 2015, 02:07
Expert's post
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enigma123 wrote:
The class mean score on a test was 60, and the standard deviation was 15. If Jack's score was within 2 standard deviations of the mean, what is the lowest score he could have received?

(A) 30
(B) 31
(C) 45
(D) 90
(E) 89

Check Standard Deviation Questions in our Special Questions Directory.
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Re: The class mean score on a test was 60, and the standard deviation was [#permalink]

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06 May 2015, 02:09
Expert's post
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Re: The class mean score on a test was 60, and the standard deviation was [#permalink]

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17 Mar 2016, 10:54
I assumed the answer was B because it asked for Jack's score within 2 standard deviations of the mean.

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Re: The class mean score on a test was 60, and the standard deviation was [#permalink]

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17 Mar 2016, 23:57
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saiesta wrote:
I assumed the answer was B because it asked for Jack's score within 2 standard deviations of the mean.

"Within" includes the edge. e.g.
Buy a jacket within 200 dollars.
So you are allowed to buy a jacket of 200 dollars too.
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Kudos [?]: 17765 [2], given: 235

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The class mean score on a test was 60, and the standard deviation was [#permalink]

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14 Oct 2016, 23:11
The class mean score 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?

Last edited by Vyshak on 14 Oct 2016, 23:20, edited 1 time in total.
Topic Merged. Refer to the above discussions

Kudos [?]: 5 [0], given: 6

The class mean score on a test was 60, and the standard deviation was   [#permalink] 14 Oct 2016, 23:11
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