prep上一道关于standard deviation的题目,望赐教~

Christine瓜瓜 · 发表于 2010-10-27 12:34:35

70,75,80,85,90,105,130,130,130.
This list shown consists of times, in seconds, that it took each of 10 schoolchildren 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 runnings times are more than 1 standard deviation below the mean of the 10 running times?

答案是2~~~

lisa78 · 发表于 2010-10-27 14:48:10

话说，第一排只有9个数啊，没有少一个数吗？
算出mean是多少，比（mean-22.4)还大的，数数有几个就出来了。
应该是这样吧，求证实

cs_bluetooth · 发表于 2010-10-27 14:53:02

hehe 应该是吧

prep上一道关于standard deviation的题目,望赐教~

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