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Homework Help: Probability questions?

  1. Nov 29, 2005 #1
    How to calculate the probability of this questions?

    Supposed there are m bukcets, n balls. use function f(x) to decide which bucket the ball go. Supposed that the probability a ball going to 0-j is 0.9 and going to j -> m-1 is 0.1. What's the probability of for every bucket there is at least one ball?

    I really get stuck.

    Any help appreciated!
  2. jcsd
  3. Nov 29, 2005 #2


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    I do not understand what you mean by "a ball going to 0-j" or "going to j -> m-1 ". I presume that you have the buckets labeled 1 to m by "m-1" you mean the bucket labeled that way- but what is j?
  4. Nov 29, 2005 #3
    Yes, the buckets are labeled from 0 to m-1,
    the probaiblity that a ball going to buckets(from 0 to j-1) is 0.9, and going to j-1 to m-1 bucket is 0.1. and inside [0, j-1] and [j-1, m-1] is equally. j is only a number. for example if m=4, j=2 and p(a ball go to bucket 0,1) = 0.9 and p(go to bucket 2,3)=0.1
  5. Nov 30, 2005 #4


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    HINT: Calculate the probability that a bucket contains no balls - it is a binomial distribution.

    Also, are you sure the two bucket ranges overlap??
  6. Nov 30, 2005 #5
    Thanks a lot. Yes I made a mistake here, the latter should be j -> m-1.
    Your advice is really helpful..
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