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The residents of Town X participated in a survey [#permalink]

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01 Sep 2009, 15:11

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The residents of Town X participated in a survey to determine the number of hours per week each resident spent watching television. The distribution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours. The number of hours that Pat, a resident of Town X, watched television last week was between 1 and 2 standard deviations below the mean. Which of the following could be the number of hours that Pat watched television last week?

First of all,I would suggest you to go through some documentation about means, medians, mode, standard deviations etc..It is good to know some theory as well..

Now, about the problem, Given, Mean = 21 ; S.D = 6

Now, any value which is 1 standard deviation above the mean is = mean + S.D = 21 + 6 = 27

any value which is 1 standard deviation below the mean is = mean - S.D = 21 - 6 = 15

any value which is 2 standard deviation above the mean is = mean + 2* S.D = 21 + 2*6 = 33

any value which is 2 standard deviation below the mean is = mean - 2* S.D = 21 - 2*6 = 9

question is asking for that value which is between 1 and 2 S.D below the mean..i.e. between 9 and 15

only 12 lies between 9 and 15.. hence, the answer is 12..

I CAN NOT READ THE QUESTION. PLEASE, POST IT CLEARLY. GMATPREP QUESTIONS IS GOOD ONES TO STUDY

You should click the image to zoom in. Anyway here is the question:

The residents of Town X participated in a survey to determine the number of hours per week each resident spent watching television. The distribution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours. The number of hours that Pat, a resident of Town X, watched television last week was between 1 and 2 standard deviations below the mean. Which of the following could be the number of hours that Pat watched television last week? A. 30 B. 20 C. 18 D. 12 E. 6

Given: mean=21 and SD=6.

The number of hours that Pat watched television was between 1 and 2 standard deviations below the mean: 1 SD below the mean is mean-1*SD=15 and 2 SD below the mean is mean-2*SD=9, so the number of hours that Pat watched television was between 9 and 15 hours.

The residents of Town X participated in a survey [#permalink]

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23 Jul 2016, 04:03

GODSPEED wrote:

The residents of Town X participated in a survey to determine the number of hours per week each resident spent watching television. The distribution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours. The number of hours that Pat, a resident of Town X, watched television last week was between 1 and 2 standard deviations below the mean. Which of the following could be the number of hours that Pat watched television last week?

A. 30 B. 20 C. 18 D. 12 E. 6

Mean =21 ; SD= 6 Mean -1 SD= 21-6=15 Mean-2SD - 21- 12 = 9

Range {From 1 SD to 2SD} = 9 to 15 What value lies between 9 to 12 that matches our options ===> 12 ANSWER IS D
_________________

Posting an answer without an explanation is "GOD COMPLEX". The world doesn't need any more gods. Please explain you answers properly. FINAL GOODBYE :- 17th SEPTEMBER 2016. .. 16 March 2017 - I am back but for all purposes please consider me semi-retired.

Re: The residents of Town X participated in a survey [#permalink]

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09 Aug 2017, 12:27

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