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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 Tv last week was between 1 and 2 standard deviation below the mean,which of the following could be the the number of hours that pat watched TV last week?
答案是12 ，我只要是看不明白题目中给的那个条件到底是什么意思，就是说 标准差低于mean 1 and 2,好像这种类型的题目我也遇到过 但是都不明白到底怎么解！请大家指导！非常感谢！在线等！ |
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发表于 2009-11-7 17:08:20
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