哎呀哎呀 急问一个关于deviation的问题啊 跪求解答

翁羽凌虚

PREP模考里面有一个数学题 说什么 一堆数的平均值和deviation分别是 13.5 和1.5 让求什么2 standard deviation是什么？答案是10.5.为什么啊？？？？ deviation和standard deviation不是一个东西？ 哎呀 反正原题我忘记了 然后又脑残的把这次模考取消了 然后就扯了。。。。。拜托大家帮忙解答一下

小球儿滚滚

我记得我好像做到过这道题目，仔细看一下题目就可以了哦，原题目是：mean=13.5,deviation=1.5, what's the exactly value of 2 standard deviations less than the mean
你再仔细看一下吧

clytzejjx

deviation 应该是方差
standard deviation 应该是标准差

前者应该是后者的平方~ 但是这个题没看懂

小唯唯

what's the exactly value of 2 standard deviations less than the mean
就是用13.5-3就对了………………

nrnr

2 standard deviations away from the mean refers to the range between (mean- 2 X std dev) and (mean + 2 std deve). in this case, it should be (13.5-1.5X2) to (13.5+1.5X2).. that is 10.5 to 16.5...
you may want to review Normal distribution and it will help you to understand the concept of std dev.

nrnr

I should correct my previous statement. If the question asks for specific value which is 2 standard deviations away from mean value, then the value could be 10.5 and 16.5.
If the question asks for the range of values which are within 2 std dev of the mean values, then it is from 10.5 to 16.5.

翁羽凌虚

I should correct my previous statement. If the question asks for specific value which is 2 standard deviations away from mean value, then the value could be 10.5 and 16.5.
If the question asks for the range of values which are within 2 std dev of the mean values, then it is from 10.5 to 16.5.

-- by 会员 nrnr (2011/4/27 12:05:08)

NRNR同学，谢谢你回答问题啊，那个，由于我水平有限，能不能麻烦你用中文给我讲一下啊？？？十分感谢