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Math Help - The LAst ONE.... (Big one)

  1. #1
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    Post The LAst ONE.... (Big one)

    8. Thinking, Inquiry, Problem Solving There are 25 students in a Data
    Management class. Determine the probability that at least two of them
    share the same birthday. (Assume that every year has 365 days.)
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  2. #2
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    Quote Originally Posted by wikji View Post
    8. Thinking, Inquiry, Problem Solving There are 25 students in a Data
    Management class. Determine the probability that at least two of them
    share the same birthday. (Assume that every year has 365 days.)
    Read this.
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  3. #3
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    conditional probability

    this question requires conditional probability
    i.e. probability of A = 1 - probability of B

    so we have 25 people.

    therefore the first persons birthday is 1/365.
    the probability that the next person does not have the same birthday is 364/365.
    third is 363/365.
    fourth is 362/365.
    .
    .
    .
    .
    so when we get to the 25th person, the probability that the birthdays are different is:

    364/365 * 363/365 * 362/365 * ... * 341/365.

    therefore the probability that one person has the same birthday as the other in 1 - this answer.

    = 1 - 0.431300296
    = 0.568699703

    which is approximately 57%.
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