2,3,4,5,6這五個(gè)數(shù)的平均數(shù)是4,則這組數(shù)據(jù)的方差是 .
【答案】
分析:根據(jù)方差公式S
2=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131101190712773410161/SYS201311011907127734101011_DA/0.png)
[(x
1-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131101190712773410161/SYS201311011907127734101011_DA/1.png)
)
2+(x
2-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131101190712773410161/SYS201311011907127734101011_DA/2.png)
)
2+…+(x
n-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131101190712773410161/SYS201311011907127734101011_DA/3.png)
)
2]代入相應(yīng)數(shù)值進(jìn)行計(jì)算即可.
解答:解:S
2=[(2-4)
2+(3-4)
2+(4-4)
2+(5-4)
2+(6-4)
2]÷5=2,
故答案為:2.
點(diǎn)評(píng):此題主要考查了方差公式,關(guān)鍵是熟練掌握方差公式S
2=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131101190712773410161/SYS201311011907127734101011_DA/4.png)
[(x
1-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131101190712773410161/SYS201311011907127734101011_DA/5.png)
)
2+(x
2-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131101190712773410161/SYS201311011907127734101011_DA/6.png)
)
2+…+(x
n-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131101190712773410161/SYS201311011907127734101011_DA/7.png)
)
2].