prep 数学一道。请大牛们帮忙。

kobesoros · 发表于 2010-10-25 23:55:50

The residens 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 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 deviation below the mean. Which of the following could be the number of hours that Pat watched television last week?

yexuu · 发表于 2010-10-26 08:52:50

lz把答案贴出来吧，貌似有点信息不足，只能确定是在20-21之间，而且那个6不知道怎么用

fujianaicd · 发表于 2010-10-26 09:39:51

1 and 2 standard deviation below the mean 就是一到两倍的标准差

应该在 21-6*2=9 到
21-6*1=15之间

kobesoros · 发表于 2010-10-26 19:52:14

谢谢你们的帮忙。这是我以前prep遇到的一个题目。时间长了，选项都丢了。我只想问问大家，这种题该怎么去思考。

prep 数学一道。请大牛们帮忙。

所属分类: GMAT考试

正在浏览此版块的会员 ()

浏览过的版块