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Determination of a Join pdf

  1. Dec 19, 2009 #1
    Determination of a Joint pdf

    Hi all! Someone can help me with this problem?

    The duration of a certain type of bulbs has a exponential distribution with known parameter [tex]\lambda [/tex]. Consider a set of n bulbs. Which is the joint pdf of the durations [tex]t_{i}[/tex] of the [tex]n[/tex] bulbs?
     
    Last edited: Dec 20, 2009
  2. jcsd
  3. Dec 20, 2009 #2

    statdad

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    Can you assume that the durations' distributions are independent? If so, there shouldn't be a problem.
     
  4. Dec 20, 2009 #3
    Yes the durations can be indipendent.
     
  5. Dec 20, 2009 #4

    statdad

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    What do you know about distributions of independent random variables?
     
  6. Dec 21, 2009 #5
    Is this the right answer?
    [tex]f(t_1,t_2...t_n)=\lambda^n e^{-\lambda \sum_{i=1}^{n}t_i}[/tex]
     
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