GMAT数学辅导:算术知识点全解析
5.标准方差:
One of the most common measures of dispersion is the standard deviation. Generally speaking, the greater the data are spread away from the mean, the greater the standard deviation. The standard deviation of n numbers can be calculated as follows:
find the arithmetic mean ;
find the differences between the mean and each of the n numbers ;
square each of the differences ;
find the average of the squared differences ;
take the nonnegative square root of this average.
Notice that the standard deviation depends on every data value, although it depends most on values that are farthest from the mean. This is why a distribution with data grouped closely around the mean will have a smaller standard deviation than data spread far from the mean.
上一篇: GMAT数学备考经验:通项问题
下一篇: GMAT数学必背单词:数学名词大全(一)
2016春人教PEP版英语五下《Recycle 2》ppt课件1
2016春人教PEP版英语五下Unit 3《My school calendar》(Part B)ppt课件2
2016春人教PEP版英语五下Unit 4《When is Easter》(Read,listen and chant 1)动画素材
2016春人教PEP版英语五下《Recycle 2》ppt课件3
2016春人教PEP版英语五下Unit 3《My school calendar》(Part B)ppt课件1
2016人教PEP版英语五年级下册Unit 2《My Favourite Season》(单元歌曲、单词朗读)课文录音
2016春人教PEP版英语五下Unit 4《When is Easter》ppt课件1
2016春人教PEP版英语五下Unit 6《Work quietly》(Part A)ppt课件1
2016春人教PEP版英语五下《Recycle 1》ppt课件1
2016春人教PEP版英语五下Unit 4《When is Easter》(Read,listen and chant 2)动画素材
2016春人教PEP版英语五下《Recycle 1》ppt课件2
2016春人教PEP版英语五下Unit 4《When is Easter》(Ask and answer)动画素材
2016春人教PEP版英语五下Unit 4《When is Easter》(Let’s sing)动画素材
2016春人教PEP版英语五下Unit 4《When is Easter》ppt课件3
2016春人教PEP版英语五下《Recycle 1》ppt课件
2016人教PEP版英语五年级下册Unit 2《My Favourite Season》(PART A)课文录音
2016人教PEP版英语五年级下册Unit 2《My Favourite Season》(PART B)课文录音
2016人教PEP版英语五年级下册Unit 1《My Day》(单元歌曲、单词朗读)课文录音
2016春人教PEP版英语五下Unit 6《Work quietly》(Part B)ppt课件2
2016春人教PEP版英语五下Unit 4《When is Easter》(Let’s learn 2)动画素材
2016春人教PEP版英语五下Unit 4《When is Easter》(Talk about)动画素材
2016春人教PEP版英语五下Unit 4《When is Easter》ppt课件5
2016春人教PEP版英语五下Unit 4《When is Easter》ppt课件4
2016春人教PEP版英语五下Unit 3《My school calendar》ppt复习课件
2016人教PEP版英语五年级下册Unit 1《My Day》(PART C)课文录音
2016春人教PEP版英语五下Unit 3《My school calendar》(Part A)ppt课件1
2016春人教PEP版英语五下Unit 3《My school calendar》(Part A)ppt课件3
2016春人教PEP版英语五下Unit 5《Whose dog is it》ppt复习课件
2016春人教PEP版英语五下《Recycle 1》ppt课件3
2016春人教PEP版英语五下Unit 4《When is Easter》(Part B)ppt课件3