prep math 关于标准差的经典问题

yalemba

8 numbers: 9.4 9.9 9.9 9.9 10.0 10.2 10.5
mean:10
standard deviation 0.3

question: what is the percent of the 8 numbers within 1 standard deviation of the mean?

3X

wechinas

You just outlined 7 numbers... But still, for the method, why not just

count the numbers within one deviation of the mean(9.7-10.3) and get the

answer readily?

yalemba

thank you

there should be 8 figures

I misunderstood 1 standard deviation and standard deviation=1

and thinking why the deviation is changing from 0.3 to 1

emma-maple

实在对不起,就是把这道题的单词都查一遍,我还是不懂什么意思,恳请哪位把我绕出来吧......

sheeper2008

有8个数字(我漏掉了另外一个10.2)
均值10 方差0.3
问8个数中，距离一个方差之内的个数占总数的百分比