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[求助]Gmat prep里的数学第一套32题
The residents of Town X participated in a
survey to determine the number of hours per week each resident spent watching
TV. 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 TV 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 TV last
week? 30; 20; 18; 12; 6. The answer is D, but I choose C.....Thank you.
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