On a roulette table with a single green zero the probability of the ball landing in a red pocket is 18/37 or 19/18 against (or approx 49% - with the odds for it landing in a non-red pocket (black or green) being approx 51%.(adsbygoogle = window.adsbygoogle || []).push({});

Probability theory tells us that although the ball will, at times, land in a non-red pocket several times in succesion, and, at times,manytimes in succession, in the LONG RUN it will land there approx 51% of the time (assuming an unbiased wheel etc).

But what is the LONG RUN?

A gambler can bet on red only to see the ball land in black (or green) say, 10 times in a row. Another gambler may see the ball land in black (or green) 15 or 20 times in a row (a freakish occurrence for some, but unremarkable for the mathematician – or experienced croupier).

Q. What is the ‘record’ for successive non-reds in actual play over the few centuries that roulette has been around?

Q. As a thought experiment, if we had monitored an unbiased wheel (with all other factors not causing any bias either) for the last two or three centuries what could the ‘record’ be in this case for successive non-reds?

Q. Does probability theory suggest that if we played for a long enough period of time we would see a hundred non-reds in succession? A thousand? Million? Billion, trillion etc?

Q. How can we predict when the LONG RUN (whatever that may be) will show us the true odds realised, ie, when we see there has been approximately 49% reds, 51% non-reds?

Q. If it’s the case that in theory we could see black come up say, a million times in a row (or more), is it true that (given sufficient spins) it would be the casein practice?

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# B Probability; what is "the long run"?

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