设随机变量X与Y相互独立,且D(X)=D(Y)=1,则D(X-Y)=____.
设随机变量X与Y相互独立,且D(X)=D(Y)=1,则D(X-Y)=____.
【正确答案】:2。解析:D(X-Y)=D(X)+D(Y)=2.
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