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# The distribution of the numbers of hours that students at a certain co

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Joined: 02 Sep 2009
Posts: 55706
The distribution of the numbers of hours that students at a certain co  [#permalink]

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24 May 2019, 01:52
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Difficulty:

25% (medium)

Question Stats:

79% (01:04) correct 21% (00:59) wrong based on 27 sessions

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The distribution of the numbers of hours that students at a certain college studied for final exams has a mean of 12 hours and a standard deviation of 3 hours. Which of the following numbers of hours are within 2 standard deviations of the mean of the distribution?

I. 10
II. 14
III. 16

A. I only
B. II only
C. III only
D. I and III only
E. I, II and III

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Re: The distribution of the numbers of hours that students at a certain co  [#permalink]

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24 May 2019, 04:21
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Bunuel wrote:
The distribution of the numbers of hours that students at a certain college studied for final exams has a mean of 12 hours and a standard deviation of 3 hours. Which of the following numbers of hours are within 2 standard deviations of the mean of the distribution?

I. 10
II. 14
III. 16

A. I only
B. II only
C. III only
D. I and III only
E. I, II and III

Numbers with in 2 standard deviation from the mean = Numbers with in M+2SD and M-2SD

i.e. Numbers between 12-2*3 and 12+2*3 = Numbers between 6 and 18 = {10, 14, 16} all are in the range hence

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Re: The distribution of the numbers of hours that students at a certain co  [#permalink]

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24 May 2019, 10:52
Bunuel wrote:
The distribution of the numbers of hours that students at a certain college studied for final exams has a mean of 12 hours and a standard deviation of 3 hours. Which of the following numbers of hours are within 2 standard deviations of the mean of the distribution?

I. 10
II. 14
III. 16

A. I only
B. II only
C. III only
D. I and III only
E. I, II and III

value = m+sd
value = 12+2*3 ; 18 & other value ; 12-2*3 =6
all given values fall in range
IMO E
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Re: The distribution of the numbers of hours that students at a certain co   [#permalink] 24 May 2019, 10:52
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# The distribution of the numbers of hours that students at a certain co

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