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Homework Help: Rational Function Question

  1. Dec 15, 2007 #1
    1. The problem statement, all variables and given/known data
    Queuing Theory (study of lines for stores) says that for a drive through window at a Macdonalds, the function

    f(x)= 9/(x(x-9))

    represents the average time in hours a customer will wait in line. X=average number of people an hour.
    How long will a customer have to wait in line (on average)?

    3. The attempt at a solution

    Not sure at all on how to find an average time out of this function.
  2. jcsd
  3. Dec 15, 2007 #2


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    Were you given a value for x?
  4. Dec 15, 2007 #3
    The question I think says 9<x<or=20
  5. Dec 15, 2007 #4


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    Yes, x will have to be larger than 9 for that function to be positive- and I've never had a negative waiting time at McDonald's! The average of a function, f(x), over [itex]a\le x\le b[/itex] is
    [tex]\frac{\int_a^b f(x)dx}{b-a}[/tex]
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