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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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David C. Ullrich

Posts: 21,553
Registered: 12/6/04
Re: probability question about the dice game
Posted: Feb 15, 2013 10:22 AM
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On Thu, 14 Feb 2013 13:34:21 -0800 (PST), wrote:

>On Thursday, February 14, 2013 6:05:23 PM UTC, Jussi Piitulainen wrote:
>> 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).

What??? I didn't say anything about probabilities! I said
something about odds, in particular terminology
used to express statements about odds.
Here's what I actually said, with a little context:

>> >>> from itertools import product
>> >>> die = {1,2,3,4,5,6}
>> >>> dice = set(product(die, die, die, die))
> > >>> sum(int(max(a,b) > max(c,d)) for a,b,c,d in dice)

>> 505
>> >>> sum(int(max(a,b) <= max(c,d)) for a,b,c,d in dice)
>> 791


>>I'd say her odds are 505 for and 791 against. I hope my gambling
>>vocabulary is not too far off.

>The terminology would be "her odds of winning are 505 to 791".

Nothing at all about probability. Look at the code I was referring
to: There are 505 equally likely cases leading to a win and 791
equally likely cases leading to a loss. That makes the odds of
winning precisely 505 to 795.

In particular, I said nothing at all about the math, my only
comment was about terminnology (this has something to do
with the fact that the OP's question was about terminolopgy).
It's beyond me what makes you think I said anything about
any probability being X/(X+Y).

And btw the terminology I gave _is_ perfectly standard.
To know that it's not you'd need to... never mind.


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