大神们,概率论与数理统计题目求解呀~
1个回答
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Z服从f(x,y)
X,Y独立
f(x,y)=f(x)f(y)=1/100
Z=1000Y(Y≤X)
Z=1000X+500(Y-X)=500X+500Y (Y>X)
E(Z)=∫(10~20)dx∫(10~x)1000yf(x,y)dy+∫(10~20)dy∫(10~y)(500X+500Y)f(x,y)dx
=∫(10~20)dx∫(10~x)10ydy+∫(10~20)dy∫(10~y)(5X+5Y)dx
=20000/3+7500
=42500/3
X,Y独立
f(x,y)=f(x)f(y)=1/100
Z=1000Y(Y≤X)
Z=1000X+500(Y-X)=500X+500Y (Y>X)
E(Z)=∫(10~20)dx∫(10~x)1000yf(x,y)dy+∫(10~20)dy∫(10~y)(500X+500Y)f(x,y)dx
=∫(10~20)dx∫(10~x)10ydy+∫(10~20)dy∫(10~y)(5X+5Y)dx
=20000/3+7500
=42500/3
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