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Math Help - Random Variables

  1. #1
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    Random Variables

    In order to verify the accuracy of their financial accounts, companies use auditors on a regular basis to verify accounting entries. The company's employees make erroneous entries 2% of the time. Suppose that an auditor randomly checks five entries. Let Y be the number of errors detected by the auditor.

    a) What are the possible values of the random variable Y?
    b) Find the probability function for Y.
    c) Find the probability distribution function for Y.

    My answer:
    a) Y = {0,1,2,3,4,5}.
    b) y 0 1 2 3 4 5
    p(y)

    I am stuck on finding the probability function for Y. Do I use the formula C(6,y)(0.02)^y(0.98)^(n-y)? Find the combination of six possibilities chosen y at a time, then multiply that by (0.02) raised to the y power, then multiply that by 0.98 raised to the (n-y).
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  2. #2
    Grand Panjandrum
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    Re: Random Variables

    Quote Originally Posted by lovesmath View Post
    In order to verify the accuracy of their financial accounts, companies use auditors on a regular basis to verify accounting entries. The company's employees make erroneous entries 2% of the time. Suppose that an auditor randomly checks five entries. Let Y be the number of errors detected by the auditor.

    a) What are the possible values of the random variable Y?
    b) Find the probability function for Y.
    c) Find the probability distribution function for Y.

    My answer:
    a) Y = {0,1,2,3,4,5}.
    b) y 0 1 2 3 4 5
    p(y)

    I am stuck on finding the probability function for Y. Do I use the formula C(6,y)(0.02)^y(0.98)^(n-y)? Find the combination of six possibilities chosen y at a time, then multiply that by (0.02) raised to the y power, then multiply that by 0.98 raised to the (n-y).
    The number of errors would have a binomial distribution B(5,0.2)

    CB
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  3. #3
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    Re: Random Variables

    Why is the binomial distribution B(5, 0.2) instead of B(6, 0.2)? Does that mean part a should be Y = {1,2,3,4,5}? I thought there had to be an option of getting 0 errors.
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  4. #4
    Grand Panjandrum
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    Re: Random Variables

    Quote Originally Posted by lovesmath View Post
    Why is the binomial distribution B(5, 0.2) instead of B(6, 0.2)? Does that mean part a should be Y = {1,2,3,4,5}? I thought there had to be an option of getting 0 errors.
    5 is the number checked

    Binomial distribution - Wikipedia, the free encyclopedia

    CB
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