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Topic: probability question about the dice game
Replies: 21   Last Post: Feb 18, 2013 2:47 PM

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Paul

Posts: 474
Registered: 7/12/10
Re: probability question about the dice game
Posted: Feb 14, 2013 4:34 PM
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On Thursday, February 14, 2013 6:05:23 PM UTC, Jussi Piitulainen wrote:
> pepstein5@gmail.com writes:
...
>
> >
>
> > David Ullrich is wrong. "X to Y" means that the probability of
>
> > winning is (X + Y)/Y.
>
>
>
> Which you later corrected to the reciprocal X/(X + Y); probabilities
>
> need to be between 0 and 1. But then it seems to me that Ullrich says
>
> the same, and that's also what I meant.
>


No, the reciprocal of (X + Y)/ Y is Y/(X + Y) which is what I should have said.
Ullrich wrongly said X/(X + Y).
>
> My expression above is still off. I appreciate the input. Thanks.
>
>
>

> > "X to Y against" means that the probability of winning is (X + Y)/Y
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> > and X is larger than Y.
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>
>
> The probability should be X/(X + Y). Also, X _smaller_ than Y, so that
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> the odds are against one who bets on the outcome associated with X,
>
> right?
>

No, Y/(X + Y) is correct.

> > "X to Y on" means that the probability of winning is (X + Y)/Y and X
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> > is less than Y.
>
>
>
> Similarly, X/(X + Y) but now X _larger_ than Y, right?
>
>
>

> > In this context "on" and "against" are redundant. However, these
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> > words enable useful abbreviations as follows. "Twos on" means " 1
>
> > to 2 " "Twos against" means "2 to 1". You can also write a slash
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> > "/" instead of the word "to".
>
>
>
> Odds are treated as the numerical fractions suggested by the notation
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> when one calculates things like log odds. Would X/Y be read "X to Y"
>
> in that context?
>
>
>
> Some day I'll dig up the books where I've seen these used. Mainly a
>
> collection of I.J. Good and the posthumous E.T. Jaynes volume.






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