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Probability Formula?

Discussion in 'Online Casinos' started by humannn, Mar 20, 2006.

    Mar 20, 2006
  1. humannn

    humannn Dormant account

    Occupation:
    Athlete
    Location:
    Lisbon
    Hi Everyone:

    I'd like to know the formula for figuring out the probability of getting an X number of "tails" in a row (e.g. you have a 4 percent chance of flipping tails five times in a row). But what does the math actually look like?

    I used a coin as an example, but it could also apply to Craps, Roulette, Blackjack, etc.

    Thank you.
     
  2. Mar 20, 2006
  3. GrandMaster

    GrandMaster Ueber Meister CAG

    Occupation:
    Mathematician by day, online gambler by night.
    Location:
    UK
    If the probability of an event is p, then the probability of it happening n times in a row is p^n (p to the power of n). In the case of a coin toss, p=1/2, so the probability of 5 tails in a row is 1/2^5=1/32=0.03125=3.125%.
     
    4 people like this.
  4. Mar 21, 2006
  5. humannn

    humannn Dormant account

    Occupation:
    Athlete
    Location:
    Lisbon
    Thank you for the answer, GrandMaster.

    So the 3.125% figure would be the odds of flipping tails 5 times in a row out of only 5 total flips, correct? Slim odds, indeed. Do you know how to figure out how many times 5 in a row would occur in an x number of flips? Say 100?
     
  6. Mar 22, 2006
  7. Zoozie

    Zoozie Ueber Meister CAG PABnonaccred

    Occupation:
    Software Developer
    Location:
    Denmark
    T=tail

    You need to specify this a little more precise. Do you mean flip a coin 100 times and then count number of times you have 'blocks' with TTTTT
    If you hit 10 T's in a row, do this only count as 1 or actually as 5? What if you hit 7 T's in a row etc.

    Maybe you mean the following: what is the probability that 5 T's will occur (once or more) in a row when you flip a coin 100 times.
    I ran a simulation for this problem and it gave:

    total number of succes:9721241
    total game starts:12000000 (I ran 12M simulations each of flipping a coin 100 times)
    Probability:0.8101 (81.01%)

    I can change the following parameters if this simulation is usefull to anyone.
    I generalized it to throwing a n-sided dice and counting the max number instead of flipping a coin. The problem seems hard to solve excact with math, so it was
    much faster to just simulate it.

    numberInARowNeeded=5;
    numberOfTries=100;
    sidesOnDice=2;


    Zoozie
     
    1 person likes this.

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