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Topic: Beating the Odds?
Replies: 35   Last Post: Feb 6, 2013 3:44 PM

 Messages: [ Previous | Next ]
 Frederick Williams Posts: 2,164 Registered: 10/4/10
Re: Beating the Odds?
Posted: Jan 31, 2013 6:27 PM

pepstein5@gmail.com wrote:
>
> On Wednesday, January 30, 2013 3:14:00 PM UTC, David C. Ullrich wrote:

> > On Wed, 30 Jan 2013 00:29:09 -0800, William Elliot <marsh@panix.com>
> >
> > wrote:
> >
> >
> >

> > >There is a fair coin with a different integer on each side that you can't
> >
> > >see and you have no clue how these integers were selected. The coin is
> >
> > >flipped and you get to see what comes up. You must guess if that was the
> >
> > >larger of the two numbers or not. Can you do so with probability > 1/2?
> >
> >
> >
> > Of course not. Seeing one side gives you no information about
> >
> > what's on the other side.

>
> I don't completely agree with this answer. The concept of a number being selected such that "you have no clue how it was selected" doesn't translate readily into mathematics. If it's mathematics, you need to specify the procedure or specify the proability space (or set of possible probability spaces) etc.
>
> Since this isn't mathematics, the best I can do is use intuition and commonsense. Surely, if one of the numbers was > 10 ^ 1000, the most intelligent guess is that the number on the reverse side is smaller.
>
> Here's my algorithm: If the number < 0, I will say that the number on the current face is smallest. if the number > 100, I will say that the reverse number is smallest. Otherwise, I will answer randomly.

How do you choose an integer randomly?

> This would probably be better than 50/50.

With an answer to my question (with 'pseudo randomly' in place of
'randomly' if you like) you could simulate it and report back.

> Alternatively (and probably a better approach), I note that there are three possible answers: A) Yes, such an algorithm exists, B) No such algorithm exists C) The problem is insufficiently specified.
>
> You went for answer B but I would go for C.
>
> Paul Epstein

--
When a true genius appears in the world, you may know him by
this sign, that the dunces are all in confederacy against him.
Jonathan Swift: Thoughts on Various Subjects, Moral and Diverting

Date Subject Author
1/30/13 William Elliot
1/30/13 forbisgaryg@gmail.com
1/31/13 William Elliot
2/1/13 forbisgaryg@gmail.com
2/1/13 Dan Heyman
1/30/13 David C. Ullrich
1/30/13 Steve Oakley
1/31/13 Paul
1/31/13 Frederick Williams
1/31/13 David Petry
2/1/13 Richard Tobin
2/1/13 David C. Ullrich
2/1/13 Paul
2/2/13 Jim Burns
2/2/13 Jim Burns
2/2/13 Paul
2/2/13 David C. Ullrich
2/2/13 David C. Ullrich
2/2/13 Paul
2/3/13 David C. Ullrich
1/31/13 Frederick Williams
1/31/13 Butch Malahide
1/31/13 JohnF
2/1/13 ArtflDodgr
2/1/13 Butch Malahide
2/2/13 William Elliot
2/2/13 Paul
2/3/13 quasi
2/3/13 Paul
2/3/13 Paul
2/3/13 quasi
2/3/13 quasi
2/3/13 Butch Malahide
2/6/13