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Thread: tricky algebra: With a fair coin, my opponent flips 50 times, with fair odds, ie,...

  1. #11
    Hi 'tkhunny' - as to your questions


    1) Yes, as we don't know whether any flip will be a win or lose.


    2) No


    3) "proportion" just means how much we bet each time.


    All my efforts, I'm afraid, have not worked. Hence I tried this website.
    I left school too long ago to remember my A level work.
    Thought it would be a good question for people that like problem solving.

  2. #12
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    You earned my respect by simply answering my questions.

    1) If you lose 15 in a row, you will lose only 15 - one each round.
    2) If you win 15 in a row, you win 32,767 - twice as much for each of 15 rounds.
    3) The unfortunate thing is the utter and complete loss of everything because of the bet-doubling. If you win 14 in a row and lose the last, you're still a dollar down after 15 rounds.
    4) The probability of being ahead after 15 rounds is 29.66%. Mostly, this is a result of the odd wiping-out of everything after a single loss.
    5) A cute histogram of outcomes

    Bin Frequency %
    -100 13,012 39.71%
    -50 4,752 14.50%
    -20 3,624 11.06%
    -10 992 3.03%
    670 2.04%
    10 454 1.39%
    20 430 1.31%
    50 1,080 3.30%
    100 1,296 3.96%
    More 6,458 19.71%

    "-50" means "a loss of 50 or more, but not so much as 100", eg. -50.00 - -99.99.
    "100" means "a gain of 100 or less, but not so little as 50", eg +50.01 - 100.00

    Like I said, spreadsheets work. It will take a substantially different betting strategy to improve the outcome.
    Last edited by tkhunny; 11-22-2017 at 06:28 PM.
    "Unique Answers Don't Care How You Find Them." - Many may have said it, but I hear it most from me.

  3. #13
    Hi tkhunny

    I wasn't thinking of using a spreadsheet, is this Excel?
    I gather the formula used is, on a win, double the bet, on a lose, back to 1?

    Cheers
    Dave

  4. #14
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    Your instruction was to maintain the bet on a loss, not reset to 1.

    I used MS Excel 2016. It was tedious, but not particularly difficult.
    "Unique Answers Don't Care How You Find Them." - Many may have said it, but I hear it most from me.

  5. #15
    I didn't give any instructions.

    That was the question in the first place, how much to bet each time.

  6. #16
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    Quote Originally Posted by daveylibra View Post
    I didn't give any instructions.

    That was the question in the first place, how much to bet each time.
    Yes, you did.

    Review:

    2) Do you reset back to the initial amount on a loss? Maybe just 1/2 and back to where you were on the previous bet.

    Hi 'tkhunny' - as to your questions

    2) No
    "Unique Answers Don't Care How You Find Them." - Many may have said it, but I hear it most from me.

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