一道prep数学~求题干翻译~

陌下清风 · 发表于 2010-10-14 13:35:30

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 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 TV last week?

前面我看懂了，主要想问问划红线的部分“between 1 and 2 standard deviations below the mean”是什么意思？有点晕...
大家帮我看一下~~万分感谢~~

Brilliance · 发表于 2010-10-14 13:47:20

就是均值一下1到2个标差之间也就是21-6=15与21-6*2=9之间
希望可以帮到你~

陌下清风 · 发表于 2010-10-15 20:40:54

恩，我明白了，谢谢你~

一道prep数学~求题干翻译~

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