设随机变量X的分布律为P{X=k}=k/15,k=1,2,3,4,5,试求:(1)P{1/2<X<5/2}; (2)P{1<=X<=3}; (3)P{X>3}. 设随机变量X的概率分布为P(X=k)=k/15，k=1，2，...

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P(1/2<x<5/2)=P(x=1)+P(x=2)=1/15+2/15=1/5
P(1\u2264x\u22642)=P(x=1)+P(x=2)=1/15+2/15=1/5
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P{1/2<X<5/2}=1/15+2/15=1/5,(x=1\u6216\u80052)
P{1<=X<=3}; =1/15+2/15+3/15=2/5
(3)P{X>3}.=3/5\uff08x=4\u30025\uff09
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P{1/2<X<5/2}=1/15+2/15=1/5,(x=1或者2)
P{1<=X<=3}; =1/15+2/15+3/15=2/5
(3)P{X>3}.=3/5（x=4。5）

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璁鹃殢鏈哄彉閲廥鐨勫垎甯冨緥涓篜{X=k}=k/15,k=1,2,3,4,5,璇曟眰:(1)P{1/2<X<...
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