单项选择题
A.(-0.127,,0127)B.(-0.156,0.156)C.(-0.115,0.115)D.(-0.129,0.129)
A.P(AB)=P(A)P(B)B.P(BC)=P(B)P(C)C.P(AC)=P(A)P(C)D.P(ABC)=P(A)P(B)P(C)
A.设c为常数,则D(c)=0B.设X为随机变量,c为常数,则有D(cX)=c2D(X)C.设X为随机变量,c为常数,则有D(c+X)=D(X)D.设X、y是两个相互独立,则有D(X+y)=D(X)+D(y)