设事件A、B相互独立,P(AUB)=0.6,P(A)=0.4,则P(B)=_______设随机变量X~B(400,0.1),则D(X)=_______设X~U(1,4),则X的密度函数f(x)=________设X~N(3,4),P{X>c}= P{X≤c},则c=________设X~N(10,100),则D(X)=______