单选题 9.设相互独立的两随机变量X，Y，均服从E(1)分布，则P{1＜min(X，Y)≤2}的值为( )

【正确答案】 D

【答案解析】P{1＜min(X，Y)≤2}=P{min(X，Y)＞1}一P{min(X，Y)＞2}
=P{X＞1，Y＞1}一P{X＞2，Y＞2}
=P{X＞1}P{Y＞1}一P{X＞2}P{Y＞2}
=e^-1.e^-1—e^-2.e^-2=e^-2—e^-4．
故选项D正确．