作者adofly (风)
看板Statistics
标题[问题] 我想请问一题有关机率的问题
时间Sat Nov 4 22:37:53 2006
Let us choose at random a point from the interval (0,1) and let the
random variable X1 be equal to the number which corresponds to that point.
Then choose a point at random from the interval (0,x1), where x1 is the
experimental value of X1. and let the random variable X2 be equal to the
number which corresponds to this point.
(a)Make assumptions about the marginal pdf f(x1) and the conditional
pdf f(X2│x1)
(b)Compute P(X1+X2>=1)
第一小题课本後面给的答案是
f(X2│x1)=1/x2 , 0<x2<x1<1
但我不了解的是为什麽机率值不等於一，而且我对f(x1)是多少也没什麽概念
第二小题课本後面给的答案是
P(X1+X2>=1)= 1 - ln2
请各位高手指点我一下，谢谢你们
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 140.120.221.74