菜鸟求助一个prep的数学题

kuraku123

希望看到这个帖子的NN们 帮忙解答一下

70，75，80，85，90，105，105，130，130，130

the list shown consists of the times, that it took each og 10 school children to run a distance of 400 M. if the standard deviation of the 10 running time is 22.4 seconds rounded to nearest tenth of a second, how many of the 10 running times are more than 1 standard deviation and blew the mean of 10 results.

A 1
B 2
C 3
D 4
E 5

kuraku123

没人解答一下吗？

kuraku123

在线等！！！！

kuraku123

在线等！！！

kuraku123

请NN们 解答一下

kuraku123

还有2个小时上考场

请问有人愿意帮忙解答一下这题吗

kuraku123

google找到答案

Calcluate the mean i,e 100


    

Now the question says values below one SD from teh mean. So find values
below (100 - 22.4 = 77.6) there are only 2 values satisfying 70 and 75


    

Note if teh question says away from mean instead of below mean then we should also consider values > 100 + 22.4


    

Hope this helps.

qianyangnet

呵呵，，，，充分证明求人不如求己啊，，，，希望你成功

xiaoy791

很简单,标准方差是用来忽悠人的

mean:100

即10个数中大于22.4小于100的数有几个,5

kuraku123

不是这个意思的