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下列说法正确的是( ) A.为了检验一批零件的质量,从中抽取10件,在这个问题中...
下列说法正确的是( )
A.为了检验一批零件的质量,从中抽取10件,在这个问题中,10是抽取的样本
B.如果x
1、x
2、…、x
n的平均数是
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605008_ST/0.png)
,那么样本(x
1-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605008_ST/1.png)
)+(x
1-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605008_ST/2.png)
)+…+(x
n-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605008_ST/3.png)
)=0
C.8,9,10,11,11这组数的众数是2
D.一组数据的标准差是这组数据的方差的平方
考点分析:
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现给出下列四个命题:
①等边三角形既是轴对称图形,又是中心对称图形;②相似三角形的面积比等于它们的相似比;
③菱形的面积等于两条对角线的积;④三角形的三个内角中至少有一内角不小于60°.
其中不正确的命题的个数是( )
A.1个
B.2个
C.3个
D.4个
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已知样本0、2、x、4的极差是6,则样本的平均数为( )
A.3
B.1
C.4或2
D.3或1
查看答案
下列运算中,错误的是( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605005_ST/0.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605005_ST/1.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605005_ST/2.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605005_ST/3.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605005_ST/4.png)
-
查看答案
数轴上表示1,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605004_ST/0.png)
的对应点分别为A,B,点B关于点A的对称点为C,则点C所表示的数是( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605004_ST/images1.png)
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605004_ST/1.png)
-1
B.1-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605004_ST/2.png)
C.2-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605004_ST/3.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605004_ST/4.png)
-2
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小明把如图所示的扑克牌放在一张桌子上,请一位同学避开他任意将其中一张牌倒过来,然后小明很快辨认出被倒过来的那张扑克牌是( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000722061060598/SYS201311030007220610605003_ST/images0.png)
A.方块5
B.梅花6
C.红桃7
D.黑桃8
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