The residents of Town X participated in a survey to determine the number of hours per week each residents spend wathcing 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 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 chould be the number of hours that Pat watched TV last week?
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发表于 2009-2-26 15:35:00
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