Jump to content



Sign up for a free account to remove the pop-up ads

Signing up for an account is fast and free. As a member you can join in the conversation, enter contests and remove the pop-up ads that guests get. Click here to create your free account.

Photo
- - - - -

The Roulette Wheel (probability) question


This topic has been archived. This means that you cannot reply to this topic.
75 replies to this topic

#1 of 76 OFFLINE   Anthony Moore

Anthony Moore

    Supporting Actor



  • 723 posts
  • Join Date: Jul 12 2001

Posted February 05 2005 - 11:02 AM

This has probably been discussed before, but I just have a probability question.

So Im sure everyone knows this roulette strategy:

Start with $10 on red or black. Lose? put down 20 on same color..lose? put down 40..80..160...320..640..

Win just one of those 7 spins in a row, and you pocket $10, and start the cycle over.

So lets say you pick red. You put all that money on red each time, having enough backup money to cover 6 losing spins.. As long as red comes up ONE time out of seven rolls, you win $10. If it doesnt, you lose everything

As long as red comes up once out of every spins, for 10 cycles in a row, thats $100.

To cover yourself for 7 spins it would cost you $2550. Its a lot of an investment, but how likely is it you will lose? Whats the probability that RED WILL or WONT come up just ONCE out of every seven spins?

So the downside is, even if you win, it will only be $10 on each cycle. But whats the odds it wont come up?

Just curious
Anthony Moore

#2 of 76 OFFLINE   James T

James T

    Screenwriter



  • 1,643 posts
  • Join Date: Aug 08 1999

Posted February 05 2005 - 12:17 PM

Red, Black, Odds, Even, 1 to 18, and 19 to 36 all have a 47.37% chance of winning.

If you want to play the odds game, play craps. If I remember my notes from highschool, it has a 51-52% winning chance.

#3 of 76 OFFLINE   Anthony Moore

Anthony Moore

    Supporting Actor



  • 723 posts
  • Join Date: Jul 12 2001

Posted February 05 2005 - 12:38 PM

but the odds have to move in your favor the more spins you get. its not just a 51% chance overall.

How would I calculate the probability of red coming up at least once in 7 spins?
Anthony Moore

#4 of 76 OFFLINE   Jason GT

Jason GT

    Second Unit



  • 452 posts
  • Join Date: Dec 12 2002

Posted February 05 2005 - 12:54 PM

I thought that someone was gonna reply with a factual post that would have obviated mine (which I didn't end up posting). Anyways...

All casino games are tilted in favour of the house.

For your original question, Anthony, of
Quote:
Whats the probability that RED WILL or WONT come up just ONCE out of every seven spins?

I'll answer the "red won't come up just once" part. From some brief research on the web, there are typically 37 spots on a roulette wheel with one of them colorless.

Therefore in a given spin, the chances of you LOSING are 19/37, or about 51.3 per cent.

The chances of you losing all seven spins (ie coming up BLACK or NO COLOR) is

(19/37)^7 = 0.00941592820025755468171924197107512

Or just under one per cent.

#5 of 76 OFFLINE   Joseph DeMartino

Joseph DeMartino

    Lead Actor



  • 8,303 posts
  • Join Date: Dec 31 1969
  • Real Name:Joseph DeMartino
  • LocationFlorida

Posted February 05 2005 - 01:11 PM

Quote:
but the odds have to move in your favor the more spins you get.


No, they don't. The table has no memory. The odds of red coming up on any given spin are exactly the same as on every other spin. It doesn't matter if black has come up on the last 1,000 spins, the odds of red coming up on the next spin are no better or worse than before. Just as with flipping a coin. The "odds" (probablities) are 50/50 every time. In a series of 100 flips you would expect to end up with roughly 50 heads and 50 tails, but if you do the experiment you will almost never end up with exactly that result. And if you've flipped the coin 90 times with a 45/45 split there is no reason you can't get 10 "heads" in a row at the end, and the chances of that last flip producing the "tails" result that it "should" are exactly the same as its coming up heads again. The odds don't change. Folks who believe otherwise are the ones who pay the bill for all that neon down in Vegas. Posted Image

Regards,

Joe

#6 of 76 OFFLINE   Jon_Are

Jon_Are

    Screenwriter



  • 2,038 posts
  • Join Date: Jun 25 2001

Posted February 05 2005 - 02:27 PM

This is one of those systems that looks good on paper but falls apart relatively easily in practice.

Five, six, seven and more consecutive blacks or reds is not at all uncommon, and that's likely all it would take to bust you.

Look at it this way, Anthony...suppose your color misses for six spins in a row. Do you really thing you have the cajones to plop down $640 for a single 50/50 (more or less) wager? Remember, by this point you're already down $630. And, even if you hit this huge bet, what are you up overall after sweating this one out? That's right: $10.

Good luck,

Jon

#7 of 76 OFFLINE   Chris Derby

Chris Derby

    Second Unit



  • 374 posts
  • Join Date: Oct 31 2000

Posted February 05 2005 - 02:30 PM

Quote:
Folks who believe otherwise are the ones who pay the bill for all that neon down in Vegas


I thought that bill was paid for by the Hoover Dam.
-derby

#8 of 76 OFFLINE   Al.Anderson

Al.Anderson

    Screenwriter



  • 2,216 posts
  • Join Date: Jul 02 2002
  • Real Name:Al

Posted February 05 2005 - 02:31 PM

Joseph laid out the statistical error with the "double" approach. The practical problem is that casinos have table min/max limits; at some point you wouldn't be able to get down your next bet to cover.

#9 of 76 OFFLINE   Anthony Moore

Anthony Moore

    Supporting Actor



  • 723 posts
  • Join Date: Jul 12 2001

Posted February 05 2005 - 03:40 PM

Quote:
Five, six, seven and more consecutive blacks or reds is not at all uncommon


does everyone believe this to be true? Because this is the factor. According to JasonGT the formula puts the odds in your favor with a 99.1% chance of victory withe a 7 spin cycle.

I do understand that this does not work..otherwise why isnt everyone doing it, right?

I just want to know where it falls apart..

So 7 in a row without hitting red one time isnt that uncommon? ( dont know, i havent played much)
Anthony Moore

#10 of 76 OFFLINE   Chu Gai

Chu Gai

    Lead Actor



  • 7,270 posts
  • Join Date: Jun 29 2001

Posted February 05 2005 - 03:45 PM

Do it with horses and start with a $2 bet Posted Image

#11 of 76 OFFLINE   Anthony Moore

Anthony Moore

    Supporting Actor



  • 723 posts
  • Join Date: Jul 12 2001

Posted February 05 2005 - 04:20 PM

Quote:
Do it with horses and start with a $2 bet


There are a lot more scenarios involved with horses. 8 horses race, right?
well, this one really only has two different outcomes ( 3 if you count the two greens)
Anthony Moore

#12 of 76 OFFLINE   Joseph DeMartino

Joseph DeMartino

    Lead Actor



  • 8,303 posts
  • Join Date: Dec 31 1969
  • Real Name:Joseph DeMartino
  • LocationFlorida

Posted February 05 2005 - 05:48 PM

Quote:
I just want to know where it falls apart...


It falls apart because of the unjustified assumption that past results affect future outcomes. You're still not getting the point that the odds don't change based on "x" number of spins. Each spin is an isolated event, independent of all previous and subsequent spins, and any "system" that assumes that certain outcomes have to obtain within a given number of spins is simply wrong.

Regards,

Joe

#13 of 76 OFFLINE   Kirk Tsai

Kirk Tsai

    Screenwriter



  • 1,424 posts
  • Join Date: Nov 01 2000

Posted February 05 2005 - 05:50 PM

The way it's talked about here, I would think in one run, seven in a row isn't that big a deal. In the long run, however, it seems like could work theoretically. But, what is large enough a sample is hard to determine.

#14 of 76 OFFLINE   Jason GT

Jason GT

    Second Unit



  • 452 posts
  • Join Date: Dec 12 2002

Posted February 05 2005 - 08:55 PM

Thanks, Joseph, for bringing up "memory" (or the lack thereof).

It falls apart because on any given spin the odds are against you winning. Over a sufficiently large number of spins, you'll lose 51% of the time. Over a sufficiently large number of spins, you will trend towards losing.

Spinning seven times in a row without hitting red is highly IMPROBABLE but it is very POSSIBLE. It's that possibility of losing where your wallet grows wings.

#15 of 76 OFFLINE   Jerry Almeida

Jerry Almeida

    Second Unit



  • 422 posts
  • Join Date: Jun 07 1999
  • Real Name:Jerry Almeida
  • LocationTampa, FL

Posted February 06 2005 - 12:25 AM

You're still not getting the point that the odds don't change based on "x" number of spins.


Well I'm still not getting it either. Posted Image

No seriously. I understand that even if I flip a coin 9 times and get 9 heads, it doesn't change the odds on the 10th flip. It's still 50/50. However, can't a series of flips be looked at as a whole different animal together?
What I'm saying is what are the odds of 10 flips all being heads or tails? Is that still 50/50? For some reason that doesn't seem accurate. Help me understand.

Besides, everyone knows that everything in life is 50/50. Either it will happen or it won't. What are the odds of me winning the lottery this weekend, well I either will or won't, so 50/50. Posted Image
Everybody relax, I'm here. -Jack Burton

#16 of 76 OFFLINE   Mike_Stuewe

Mike_Stuewe

    Stunt Coordinator



  • 140 posts
  • Join Date: Apr 07 2002

Posted February 06 2005 - 12:36 AM

Agreed about the probability of a series. It is very low. A good place to try this would be the Lady Luck casino downtown. I think the minimum spin is 50 cents.

However on your other question. If you have already flipped a coin 9 times and all 9 times it comes up heads, then the probability of the 10th time being heads is still 50/50. But, if you have yet to flip the coin, the probability of coming up with heads 10 times in a row is extremely low.

#17 of 76 OFFLINE   Bryan X

Bryan X

    Producer



  • 3,469 posts
  • Join Date: Feb 10 2003

Posted February 06 2005 - 02:22 AM

Quote:
If you have already flipped a coin 9 times and all 9 times it comes up heads, then the probability of the 10th time being heads is still 50/50. But, if you have yet to flip the coin, the probability of coming up with heads 10 times in a row is extremely low.

Exactly. The farther you are into your 10 flips of the same side, the higher the odds become that you will be successful. At the beginning, before you've flipped the coin at all, the odds of flipping the same side 10 times in a row is less than one-tenth of a percent ( about .098%). You can calculate this by:

.50 x .50 x .50 x .50 x .50 x .50 x .50 x .50 x .50 x .50 = .00098 which can also be written as .098%.

After you've flipped it once, the odds rise to just under two-tenths of a percent (about .195%).

.50 x .50 x .50 x .50 x .50 x .50 x .50 x .50 x .50 = .00195 or .195%.

The odds keep going higer the closer your streak of 'same sides' gets to 10. After 8 consecutive flips of the same side, your odds of making it to 10 are up to 25%. And after 9 flips of the same side, your odds are now at 50%.

These calculations make the assumption that you are choosing heads or tails BEFORE your first flip of the coin. The odds start out at .195% if you decide to go with whatever side comes up after your first flip.

#18 of 76 OFFLINE   Ken Chan

Ken Chan

    Producer



  • 3,302 posts
  • Join Date: Apr 11 1999

Posted February 06 2005 - 03:55 AM

Quote:
The practical problem is that casinos have table min/max limits; at some point you wouldn't be able to get down your next bet to cover.
Or you simply don't have that much to chase the double, whichever is more limiting.

Try this simulator. With the default settings, you often win a little, but occasionally lose a lot. (Let me know if there are any errors. The results run straight down the page if you're using IE, but with a more modern browser, they fill the page horizontally.)

#19 of 76 OFFLINE   Mike_Stuewe

Mike_Stuewe

    Stunt Coordinator



  • 140 posts
  • Join Date: Apr 07 2002

Posted February 06 2005 - 06:30 AM

I've been playing a free online game of Roulette. I went from 2000 to 4700 in about 20 minutes with this theory. Then I hit a string of 8 reds in a row and I lost it all.

#20 of 76 OFFLINE   D. Scott MacDonald

D. Scott MacDonald

    Supporting Actor



  • 545 posts
  • Join Date: Oct 10 1999

Posted February 06 2005 - 08:02 AM

I had this same brilliant idea while in college, but since I was a CS major I thought that I'd write a simulation and run it overnight on the computers in our lab. While it sounds like a rare probability to get a long string of the same color, in practice you will find that it happens all of the time.

As Mike discovered, the only way you can make this work for you is if you do it for a short period of time. If you play this system for any length of time, you will definitely hit the worst case scenario and lose it all. Of course that doesn't mean that you won't hit the worst case scenario on your first attempt.

Trust me, this is not a new idea, but for some reason the Casinos still manage to stay in business Posted Image
Scott


Back to After Hours Lounge



Forum Nav Content I Follow