作者a5170040 (小猪)
看板Statistics
标题[问题] 一题清大考题
时间Sat Jan 12 21:30:30 2008
Toss a fair coin and take a step of size c to the right if head shows,
to the left if tail shows. At the nth toss ,the poisition is a random
variable Xn taking the values mc ,where m=n,n-2,...,-n
a.Find P(Xn=mc)
b.Show that for large n
2
1 -m / 2n
P(Xn=mc)～ ----------- e
√(n*pi/2)
c.Find the probability that at the 50th step,X50 will exceed 6c.
麻烦各位了!实在不太清楚怎麽下手耶...
可以给个Hint也好!
谢谢!感激不尽!
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1F：推 hi123:请问m的范围有打错吗? 01/14 22:08