标准方差题!(英文版)If a certain sample of data has a mean of 20 and

标准方差题!(英文版)
If a certain sample of data has a mean of 20 and a standard deviation of 3, which of the following values is more than 2.5 standard deviations from the mean?
A. 12.0
B. 13.5
C. 17.0
D. 23.5
E. 26.5
我根本就一点都不懂方差, 除了公式! 这句话什么意思? 怎么算?
谢谢!
huahua434569 1年前 已收到2个回答 举报
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啦啦菠菜 幼苗

共回答了28个问题采纳率：85.7% 举报

如果一组数据平均值为20,而标准方差为3,下面那个数值大于2.5倍标准方差范围?
首先先算出下面所有数值和平均值20的差别
A 8
B 6.5
C 3
D 3.5
E 6.5
2.5倍标准差也就是3×2.5=7.5只有A>7.5所以选A

1年前

5

keshaner 幼苗

共回答了1个问题 举报

既然你的是英文题 我就用英文回答了
1.Formula: Z score= (X-mean)/standard deviation, that is X=mean+Z*SD(Z can be both positive and negative.)
2.I think Z score can be considered as how much times of SD is belo...

1年前

2
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