(4)、若X与Y独立，Z与Y的相关系数为
A: -4/5
B: -1
C: -1/2
D: -2/5
A: -4/5
B: -1
C: -1/2
D: -2/5
举一反三
- 若x=[1 2 3 4 5];y=[2 -1 4 3 -2];则z=x.*y=()
- 执行以下语句的结果：dict1={"x":1,"y":2,"z":3}dict2={"x":4,"a":5}dict1.update(dict2) A: {"x":1,"y":2,"z":3,"x":4,"a":5} B: {"x":4,"a":5,"x":1,"y":2,"z":3} C: 有重复项，结果有误！ D: {"x":4,"y":2,"z":3,"a":5}
- 已知E(X)= E(Y)=0, D(X)=1,D(Y)=4, ρXY =1/2 , 若Z=aX+Y与Y独立,则a等于( ) A: 2 B: -2 C: 4 D: -4
- 若a=1,x=2,y=3,z=4,则条件表达式a<;x? y:z的值是( )。 A: 5 B: 2 C: 4 D: 3
- int x=3,y,z;<br/>y=-x++;<br/>z=y+8/++x;<br/>Console.WriteLine{{0},{1},{2}",x,y,z);<br/>此程序的输出结果是____。 A: 5,-3,-2 B: 4,-3,-1 C: 4,-4,-2 D: 5,-4,-2