概率论提高二维随机变量概率统计做题本（一）解答版解答题查看解析已掌握收入错题本题讨论不看本题#8978设随机变量 XXX 的概率密度为 f(x)=kex+e−x (−∞<x<+∞)f\left(x\right) = \frac{k}{{\mathrm{e}}^{x} + {\mathrm{e}}^{-x}}\;\left({-\infty < x < + \infty }\right)f(x)=ex+e−xk(−∞<x<+∞),对 XXX 作两次独立观察,其观测值分别记为 x1,x2{x}_{1},{x}_{2}x1,x2,令 Yi={1,xi≤1,0,xi>1(i=1,2){Y}_{i} = \left\{ {\begin{array}{ll} 1, & {x}_{i} \leq 1, \\ 0, & {x}_{i} > 1 \end{array}\left({\mathrm{i} = 1,2}\right) }\right.Yi={1,0,xi≤1,xi>1(i=1,2). 求:(I) kkk 的值及 P{X1<0,X2<1}P\left\{ {{X}_{1} < 0,{X}_{2} < 1}\right\}P{X1<0,X2<1};(II) (Y1,Y2)\left({{Y}_{1},{Y}_{2}}\right)(Y1,Y2) 的概率分布.
