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Homework Help: Probability= sum of n uniformly distributed r.v.'s

  1. Sep 14, 2011 #1
    1. The problem statement, all variables and given/known data
    Xi ~ U(80,120)
    find the E[X1+X2+...+Xn]=?

    2. Relevant equations



    3. The attempt at a solution

    Why can't I do this?:
    E[X1+X2+...+Xn]=n*E[X1]
    and just find the expected value?

    Is that because the distribution changes as we increase the number of elements of uniforms we sum?
    Is there some trick here?

    I found something called "Irwin–Hall distribution"... is this it?
     
  2. jcsd
  3. Sep 14, 2011 #2

    LCKurtz

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    You can do that. The expected value operator is linear.
     
  4. Sep 14, 2011 #3
    I see, I guess the fact that the distribution changes, confused me...

    Thanks.
     
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