已知數(shù)據(jù)x1、x2、x3、x4、x5是互不相等的正整數(shù),且.x=3,中位數(shù)是3,則這組數(shù)據(jù)的方差是_.
已知數(shù)據(jù)x
1、x
2、x
3、x
4、x
5是互不相等的正整數(shù),且
=3,中位數(shù)是3,則這組數(shù)據(jù)的方差是______.
優(yōu)質(zhì)解答
根據(jù)題意,得
中位數(shù)是x
3=3;
又∵x
1+x
5+x
2+x
4=4×3=12,
不妨設(shè)x
1=1,x
2=2,
則x
4=4,x
5=5;
∴這組數(shù)據(jù)的方差為
s
2=
[(1-3)
2+(2-3)
2+(3-3)
2+(4-3)
2+(5-3)
2]=2.
故答案為:2.
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