Q&A: Roulette and Probability
Roulette and Probability
Question
A stupid question that’s been bothering me for quite a long time. In roulette, there is the same probability of red numbers coming up as black ones, and yet the red numbers always come up more often than the black ones.
What is the reason for that?
Do you think it makes sense to bet on red more than on black, or is that an irrational move, since the probability is identical?
Answer
I have no idea what goes on in roulette. But if it’s the same probability, then it can’t be that red always comes up more often. That’s an oxymoron. Unless there’s cheating, and then again it’s not the same probability.
Discussion on Answer
Then it’s not the same probability. In that case, I didn’t understand the question. If you have a loaded die that lands on 6 in 80% of the cases, would you bet on an odd result versus 6, because there are three odd faces? Obviously you go by the probability, not by the number of possible outcomes. Only when the distribution of all outcomes is uniform is the probability determined by the number of possibilities.
Only in a uniform sample space is the probability of each outcome 1 divided by the number of possibilities.
Also, the chance that two events will both occur is the product of the probabilities only when they are independent (that is, when the condition of independence holds).
A lot of people get confused and arrive at bizarre results.
When I say there’s the same probability of red coming up as black, I mean that there is the same number of red numbers as black ones, and yet the ball lands on the red numbers more often
(it’s like with a die, where one of the numbers comes up more than the others)