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Raffle winners ... and a question

Discussion in 'Oktoberfest 2012' started by Qbrozen, Sep 18, 2012.

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    Qbrozen

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    You might want to take a look at those numbers again. Your eyes are playing tricks on you. It isn't 1 - 0.9998, it is 1 - 0.99998. So its 0.00002 vs 0.0002.
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    Qbrozen

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    It is a good question. I wonder which would bring in the most buyers. Personally, if buying 100 tickets, I'd much rather be buying into 100/5000 odds than 100/45,000, even if it means I only get 1 shot.
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    elliottsb BMW CCA Director of IT

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    I'm afraid you added one too many nines. In my calculations it is 0.9998, not 0.99998. Thankfully, I used Excel for my calculations, so that eliminated the risk of my eyes playing tricks on me. ;)
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    Qbrozen

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    Ummm... no. Look at your excel. It has four 9s. But when you typed your post, you put 3. Just do the calculation. 44991/44992=.999977773826458. That's four 9s in the front there.
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    elliottsb BMW CCA Director of IT

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    You are missing the step where you have to multiply all nine probabilities together:
    0.999977778 * 0.999977777 * 0.999977777 * 0.999977776 * 0.999977776 * 0.999977775 * 0.999977775 * 0.999977774 * 0.999977774 = 0.9998.

    Trust me when I tell you that I triple-checked my calculations before posting.
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    Qbrozen

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    OK, I am not a statistics expert, but why would you multiply them? Every time they spin the barrel and pull a number is an independent event with independent odds.

    If you do what you are saying, then each ticket on the last draw has a .02% chance of winning. With 44992 tickets in there, that's a nearly 900% total chance, yes? How is that possible?

    Although, I think maybe what you are saying is that your 1/45000 chance plus your 1/44999 chance plus .... etc etc... means you get a 1/5000 chance. So it is your cumulative chances. I think I may understand that mathematically, but my logical side is telling me something is wrong there. I can't seem to get past the fact that my ticket is still 1 in over 44990 every time someone reaches their hand in there.

    BTW, I was hoping someone could clear up the statistical side for me, so I'm glad for the posts and the chance to discuss.
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    mrsbee

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    Why don't we ask the winners how they like the odds?
    steven s and elliottsb like this.
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    elliottsb BMW CCA Director of IT

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    Bingo! I think the thing that is most confusing about probability is that it is a calculation over the course of all of the drawings combined (that's why you have to multiply them). You can't apply the total chances to one specific drawing. So, the 1/5000 chances applies to a member winning one of the nine drawings, not one specific drawing of the nine.
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    elliottsb BMW CCA Director of IT

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    That's the spirit! :)

    FYI, all of the winners have been notified, and the names and chapters of the winners have been added to the raffle page.
    MrsBee likes this.
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    mrsbee

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    johnh

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    As long as I can remember, about 3 decades back, all the entries have been placed in one barrel. Way back, only one car was awarded each year but there were far fewer members to buy tickets. The stated odds used to be far better than 1 in 5,000, but that's another discussion. The "cause," by the way, is the BMW CCA treasury.
    Think about this. Since we can buy more than 1 ticket and all tickets are in one barrel, it is possible for one person to win more than one car. It would be highly unlikely, but I see nothing in the rules to prevent that.
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    CRKrieger

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    True. It is possible to win more than one car. Theoretically, one person buying nine tickets could have won them all. If we do this long enough somebody will. :eek:

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