Probability question - Yes, I was just in Las Vegas

[Hulk]

I was in Las Vegas for the NAB show a few weeks ago, and as usual I got to talking to a friend about probability at the Roulette wheel. I couldn't explain something to his satisfaction so I'm hoping someone here may be able to help me.

Let's assume that the odds on the Roulette wheel are 50/50, that is that the double zero isn't there.

Now he understands that the chances of red coming up are 50% on EVERY spin of the wheel.

The thing he doesn't understand is the following:

It is unlikely that red will come up say 10 times in a row.

I believe the odds of that are 2^10, right?

Anyway, he thinks that if red comes up nine times in a row, due to the odds of 10 red in a row being very low, somehow there are better odds on betting black. Of course this is ridiculous, but I can't think of a satisfactory way (to him anyway) to explain it to him.

Somehow he things the odds of the 10 in a row string interfere with the 50/50 odds of each spin.

How can I convince him of the truth of this situation?

 

[notfred]

Tell him that the result of any particular spin isn't affected by the results of any previous spin.

 

[Pokey007]

The roulette wheel has no memory, therefore there is the same probability at each spin. It is equally likely that it would land on red 10 times in a row as it would to start with red, and then alternate between red and black.

 

[bolido2000]

Each event is independent from each other. There is no buffer keeping track of the history.

 

[BigSmooth]

Each spin of the wheel is an independent event. Although the odds of 10 reds in a row are slim, the odds of red coming up on any given spin is constant.

Edit: too slow.

 

[Heisenberg]

If each spin is truly independent (i.e. the results from the previous spin don't influence the current one) then the odds of red are 50% each time. The odds of ten red spins is then (1/2)^10.

 

[rgwalt]

Did you use the flipping coin analogy? Each flip is independent. So is each spin of the wheel. You could hit red 9 times in a row, and then the odds on the 10th spin would still be 50/50.

Here is another way to think about it... If his system were correct (the previous 9 spins affect the outcome of the 10th spin) then there would be absolutely no way to predict odds for anything, because "luck waves" from around the world would interfer with anything that is left to random chance.

R

 

[AUMM]

the odds of getting red or black arnt 50/50, theres 0, 00 as well

 

[DT4K]

Originally posted by: AUMM
the odds of getting red or black arnt 50/50, theres 0, 00 as well

He knows that.

Let's assume that the odds on the Roulette wheel are 50/50, that is that the double zero isn't there.

 

[GasX]

Originally posted by: AUMM
the odds of getting red or black arnt 50/50, theres 0, 00 as well

way to read the whole OP...

 

[Beattie]

Originally posted by: AUMM
the odds of getting red or black arnt 50/50, theres 0, 00 as well

you missed something from the original post...

"Let's assume that the odds on the Roulette wheel are 50/50, that is that the double zero isn't there."

 

[TheBDB]

The odds of getting 10 reds in a row is the same as the odds of getting 9 reds and 1 black.

 

[Toasthead]

Originally posted by: notfred
Tell him that the result of any particular spin isn't affected by the results of any previous spin.

This is exactly correct

 

[new2AMD]

Originally posted by: Mwilding

Originally posted by: AUMM
the odds of getting red or black arnt 50/50, theres 0, 00 as well

way to read the whole OP...

lol

 

[Chaotic42]

The odds for any combination at all are 1/2^10.

RRRRRRRRRR or BBBBBBBBBB or RRBBRRBBRR, or *anything* else.

 

[notfred]

There's 13 replies to this thread so far, and only two different answers. "The spins are independent" and "You suck at reading the post"

I think that's funny.

 

[Hulk]

Thanks for the tips guys.

I'll try to explain this to him again, and then that's it, I've had it.

Boy would Quantum Physics drive this guy crazy.

 

[Pokey007]

Originally posted by: notfred
There's 13 replies to this thread so far, and only two different answers. "The spins are independent" and "You suck at reading the post"

I think that's funny.

People saying that you suck at reading the post is independent of any previous posts.

 

[GasX]

I think notfred is independently sucky...