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某班级有50名学生,期中考试数学成绩X~N(120,σ2),已知P(X>140)=0.2,则X∈[100,140]的人数为(  )
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试题【某班级有50名学生,期中考试数学成绩X~N(120,σ2),已知P(X>140)=0.2,则X∈[100,140]的人数为(  )A.5B.10C.20D.30】;主要考察你对正态分布等知识点的理解。[详细]
举一反三
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题型:不详难度:| 查看答案
A.5B.10C.20D.30
随机变量x~N(3,σ2),若P(x≤2)=0.3,则P(3<x≤4)=______.
如果随机变量ξ~N(-1,σ2),且P(-3≤ξ≤-1)=0.4,则P(ξ≥1)=______.
已知三个正态分布密度函数ϕi(x)=data:image/png;base64,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(x∈R,i=1,2,3)的图象如图所示,则(  )
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A.μ1<μ23,σ12>σ3B.μ1>μ23,σ12<σ3
C.μ12<μ3,σ1<σ23D.μ1<μ23,σ12<σ3
若随机变量X服从正态分布N(3,1),且P(2≤X≤4)=0.6826,则P(X>4)=______.
随机变量X~N(5,σ2),若P(3<X≤7)=a,则P(X≤3)的值为(  )
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A.B.1-aC.D.