设随机变量X 服从标准正态分布N(0,1),其分布函数为Φ(X),则P(X≥4)= （ ）
A. Φ(4)
B. 2Φ(4)-1
C. 1-2Φ(4)
D. 1-Φ(4)
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若φ(3)=0.9987，则标准正态总体在区间(－3，3)内取值的概率为（ ）
A. 0.9987
B. 0.9974
C. 0.944
D. 0.8413
1)Whatisthemangoingtodotonight?
A. Setuphismum’scomputer.
Buyhismumabirthdaygift.
C. Solvehisdadscomputerproblems.
D. Helphisdadchooseanewcomputer.
2)Whatdoesthemansaytheirparentswereunlucky?
A. Theyneverhadacomputeroftheirown.
B. Theyhadlittleornoexperiencewithcomputers.
C. Nobodytaughtthemhowtousecomputers.
D. Nobodyhelpedthemwiththeircomputerproblems.
建立3阶单位矩阵A的命令是（）。
A=eye(3)
B. A=eye(3,1)
C. A=eye(1,3)
D. A=eyes(1,3)
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