• 2022-07-01
    已知随机变量X~N(5,9),Y=2X+3,下列说法正确的是
    A: E(Y)=10,Var(Y)=18
    B: E(Y)=13,Var(Y)=18
    C: E(Y)=10,Var(Y)=36
    D: E(Y)=13,Var(Y)=36
  • D

    内容

    • 0

      Cans of soft drinks cost $0.30 in a certain vending machine. What is the expected value and variance of daily revenue (Y) from the machine, if X, the number of cans sold per day has E(X) = 90, and Var(X) = 40 ( ) A: E(Y ) = 27, Var(Y ) = 4.5 B: E(Y ) = 27 , Var(Y ) = 4.5 C: E(Y ) = 27 , Var(Y ) = 3.6 D: E(Y ) = 90 , Var(Y ) = 3.6

    • 1

      y 的输出结果是 var x=-10,y; x = 2*x; y = x+25;

    • 2

      若二维随机变量(X,Y)满足 Var(X﹣Y)=Var(X+Y),则X与Y不相关.( )

    • 3

      有下述JS代码:var x = 10; var y = 20;var z = x<y ? x++ : ++y ;console.log( ‘x=’ + x + ‘; y=’ + y + ‘; z=’ + z);其运行结果是( ) A: x=11; y=20; z=11 B: x=11; y=21; z=10 C: x=11; y=21; z=11 D: x=11; y=20; z=10

    • 4

      y 的输出结果是var x=-10 , y;x = 2*x;y = x+25; A: -15 B: 10 C: -5 D: 5