求问一道DS题！！

熠笛800 · 发表于 2011-10-16 21:17:27

prep 里面的一道题：
70，75,80,85,90,105,105,130,130
The list shown consists of the times, in seconds, that it took each of 10 school children to run a distance of 400 meters. If the standard deviation of the 10 running times is 22.4 seconds, rounded to the nearest tenth of a second, how many of the 10 running times are more than 1 standard deviation below the mean of the 10 running times?

不太明白“more than 1 standard deviation below the mean of the 10 running times”是什么意思...求帮忙......

求问一道DS题！！

所属分类: GMAT考试

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