作者mangogogo (mangogo)
看板Statistics
标题Re: [问题] 机率论
时间Tue May 23 16:16:20 2006
※ 引述《helloboy (小悟)》之铭言：
: 最近做习题 做到不会做的题目 我们用的书是
: Introduction to Mathematical Statistics, 6th Edition,
: by Robert V. Hogg, Joseph W. Mckean and Allen T. Craig,
: 有一题题目是
: Let the r.v.s X1 and X2 have the jpdf f(x1,x2)= 1/π,for (x1-1)^2+(x2+2)^2 < 1
: ,zero elsewhere.
: Find marginal pdf f1(x1) and f2(x2).
hint
(x1-1)^2+(x2+2)^2 <1 => the region inside a circle that the center (1,-2) and
the radius 1
f1(x1)=∫f(x1,x2)dx2
x2
f2(x2)=∫f(x1,x2)dx1
x1
: 还有一题
: Let X1 and X2 be two independent r.v.s .
: Suppose X1 and Y=X1+X2 have Poisson distributions with means μ1 and μ>μ1,
: respectively. Find the distribution of X2.
by mgf~
: 以上 X1 X2 的 1 2 为下标
: 真的有想过了~但是真的不知道怎麽做!! 麻烦高手提示一下!!
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