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Homework Help: Probability Density Function Help

  1. Oct 7, 2006 #1
    Probability Density Function....Help

    The probabiltiy density function of the time to failure of an electric component in hours is [tex]f(x)=e^{(-x/3000)/3000}[/tex] for x > 0 and f(x) = 0 for [tex] x \leq 0[/tex] determine the probability that

    a) A component last more than 1000 hours before failure
    I know how to solve this part. All I have to to is integrate the given function from [1000, infinity].

    But how do determine the number of hours at wich 10% of all the components have failed? I don't know what interval I should integrate over. Any Ideas?
    Last edited: Oct 7, 2006
  2. jcsd
  3. Oct 8, 2006 #2


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    If F(x) is the probability that a component has failed by time x, you are looking for when F(x) = .10. Can you solve that?
  4. Oct 8, 2006 #3
    yes I can. thank you!
  5. Oct 8, 2006 #4
    when I solve it as you state that is no the answer.
    any other ideas?
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