Re: Stupid question in probability that amazed me

"Andrew Au Ying Hung" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED]
> Dear all,
>
>     Here is a simple question of probability that I tried hard for a half
> day with no result.
>
> Given a game of tossing coin, not until the recent three tosses have exactly
> two heads up, I will keep tossing.
> What is the expectation of the number of toss I have the made?
>
>     The problem looks simple, but it turns out quite hard to solve, at
> least, for me. Please spend a little time to try it out ^^

Have you tried sci.math?

Cheers,
Herman Jurjus

[ comp.ai is moderated.  To submit, just post and be patient, or if ]
[ that fails mail your article to <[EMAIL PROTECTED]>, and ]
[ ask your news administrator to fix the problems with your system. ]