设二维随机变量(X,Y)的密度函数为f(x,y)=Ae^-(2x+3y),x>0,y>0,f(x...答:设二维随机变量(X,Y)的密度函数为f(x,y)=Ae^-(2x+3y),x>0,y>0,f(x,y)=0,其他 概率P(X大于Y)为A/6。概率P=∫∫f(x,y)dxdy =A∫e^(-2x)dx∫e^(-3y)dy =A*[-2e^(-2x)]|(0,+∞)*[-3e^(-3y)]|(0,+∞)=A/6 ...
概率统计问题,二维连续型随机变量,已知二维随机变量(X,Y)的联合概率密...答:5题:f(x,y)=ke^(-y), 0<x<y.(1) k ∫ [0, ∞]{ ∫ [x, ∞] e^(-y)}dx = k ∫ [0, ∞] e^(-x) = 1. --> k=1.(2) P(X+Y≤1) = ∫ [0, 1/2]{ ∫ [x,1-x] e^(-y)}dx . 以下自己算下。(3) f(x) = ∫ [x, ∞] e^(-y)dy = e^...