Why doesn't the old roulette trick work?

[Ulysses]

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I don't understand. What else is there to say?

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Do you understand now, Ed? [img]/images/graemlins/grin.gif[/img]

[Ulysses]

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That's pure nonsense.

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Haven't seen you in this thread for a while either, champ. [img]/images/graemlins/grin.gif[/img]

[Homer]

Yeah, I get it now and am more than willing to admit that I was wrong. Actually, no, not more than willing, just regular old willing. I mean, it's not like I'm eager to admit it. Anyway, seeing as how this is the first time I've ever been wrong about anything, I think I should be given a mulligan.

-- Homer

[Ulysses]

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Anyway, seeing as how this is the first time I've ever been wrong about anything, I think I should be given a mulligan.


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Fair enough. Just don't let it happen again.

[JTG51]

I didn't add anything worthwhile to the discussion the first time around, so I figure I'm better off not saying anything. [img]/images/graemlins/smile.gif[/img]

The whole problem comes down to the fact that the probability of losing an infinite series of bets approaches zero. I obviously accept that. What I have a hard time accepting is that saying the probability approaches zero is the same thing as saying it is zero. It seems to me that since there is some non-zero chance of losing every bet, given an infinite series of trials you should eventually experience an infinite losing streak. A lot of people a lot smarter than me are saying that's wrong so I suppose it is, I'm just not sure I understand why.

I should have paid better attention in my calculus classes.

[JTrout]

I suck at calculus. Formulas give me a headache. But I don't need these skills to understand that the roulette system is doomed.

It reminds me of when I was 10 and the fair came to town. There was a dice game that you bet on whether you could roll over 7, or under 7. (you got 3 to 1 on seven).
There were
some folks playing and doing this system, and winning a few quarters.
"See!" they would say, " It's foolproof!"
I was struck with the urge to run home a break my piggy bank. But a few minutes of observing, and thinking, allowed common sense to prevail.
I was fortunate enough to have been blessed with a little common sense.
With each additional bet (larger bankroll), you can get closer to a sure thing (100%), but you can NEVER reach it.

It is similar to the question of:
If I am 100 yds from the finish line, and each day I cut the distance from the finish line in half, how many days will it take me to reach the finish line?
I don't need calculus or a formula to know I'll never get there.

Same deal.
JTrout.

[WarDekar]

At least you understand what we were saying. We've wasted 50 posts talking about something that is a moot point anyway because there is no such thing as an infinite bankroll and infinite limits, so look at the time we just wasted.

Also, what I said a long time ago also holds true. Over a long period of time and a long period of bets I believe the limit will approach the chances of winning any given bet times the amount you've wagered so far, in fact I know that's the case and if anyone REALLY wants to know the math behind it I'm sure I could put it together (this is assuming the last roll wasn't the end of an incredibly long losing streak).

I just read what I wrote and it might not make sense if you don't know what I mean to begin with. I'm saying your PROFITS will approach the percentage*(amount wagered initially). So if you "roll" 100,000 times and your chances of winning any particular time is 40%, and your unit wagered to start is 1, you'll end up with a profit of 40,000. If it's 70% it will be 70,000, etc. Although if it's a value greater than 50 it will approach from the right more often than not, if it's lower than 50 from the left more often than not.

[Chris Daddy Cool]

Maybe I'm belaboring the point here and further proving my own stupidity in calculus, but with an infinite number of trials with the possible outcomes of win or loss, wouldn't there be at some point a string of infinite losses, which could theoritically begin at the the very first "roll"?
I guess I'm saying that within infinity trials, wouldn't there be an infinite streak of wins, an infinite streak of losses, and an infinite streak of random results like WLWLWLLWW?

[WarDekar]

It's basic statistics, look up a page on stats and you'll see that as the number of trials approaches infinity the probability of only losses approaches zero.

[daryn]

just joking about monty hall by the way.. it seems like it's one of those things that just keeps coming up over and over again, like dutch boyd and is moneymaker a fish?