+ Reply to Thread
Results 1 to 5 of 5

Thread: Probability of many coin flips coming up heads 65% etc.

  1. #1
    Points: 59, Level: 1
    Level completed: 18%, Points required for next Level: 41

    Posts
    2
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Probability of many coin flips coming up heads 65% etc.




    Hello, I am wondering how to calculate what the probability would be of flipping a coin, say, 250 times and having it come up heads 65% of the time. Or 500 times and 90%. Maybe I should be asking how to calculate if it will be at LEAST 65%, at least 90%, etc. I am very interested in this problem.

    Thanks a lot.

  2. #2
    Points: 4,841, Level: 44
    Level completed: 46%, Points required for next Level: 109
    Con-Tester's Avatar
    Posts
    167
    Thanks
    3
    Thanked 59 Times in 57 Posts

    Re: Probability of many coin flips coming up heads 65% etc.

    You will want to investigate the binomial distribution for this problem.

    EDIT: Where the number of trials n is large and the per-trial probability p does not differ hugely from 0.5, you can use the normal approximation to estimate the probabilities you’re after with good accuracy.
    Last edited by Con-Tester; 08-27-2015 at 02:40 AM. Reason: More info.

  3. #3
    Points: 142, Level: 2
    Level completed: 84%, Points required for next Level: 8

    Posts
    14
    Thanks
    5
    Thanked 2 Times in 2 Posts

    Re: Probability of many coin flips coming up heads 65% etc.

    http://stattrek.com/online-calculator/binomial.aspx
    here is an online automatic calculator for you. Just fill in the probability of success (0.5), number of trials (250), number of successes (65% x 250 = 162.5 -> 163).
    AT LEAST = P (X >=163)

  4. #4
    Points: 1,470, Level: 21
    Level completed: 70%, Points required for next Level: 30

    Posts
    50
    Thanks
    0
    Thanked 5 Times in 4 Posts

    Re: Probability of many coin flips coming up heads 65% etc.

    See my web pages on the subject:
    http://home.ptd.net/~artnpeg/RUNS.html

  5. #5
    Points: 59, Level: 1
    Level completed: 18%, Points required for next Level: 41

    Posts
    2
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Probability of many coin flips coming up heads 65% etc.


    Thanks a lot people this is awesome.

+ Reply to Thread

           




Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts






Advertise on Talk Stats