IAI November 2008 Examination Q8

Discussion in 'CT3' started by paryas.bhatia, May 11, 2013.

  1. paryas.bhatia

    paryas.bhatia Member

    In this question how is E(y^2) is computed? Please help.
     
    paryas.bhatia, May 11, 2013
    #1
  2. woozie.boozie

    woozie.boozie Member

    How'd they calculate E[Y^2] ? I'm stuck on this too.
    Found this old thread, thought not to create a new one.

    Can someone please help?
     
    woozie.boozie, Apr 28, 2015
    #2
  3. divyam sankharva

    divyam sankharva Member

    E(Y^2)=Var(Y)+E(Y)^2,
    from part (1) we know that E(Y)=50

    now for variance
    X follow N(0,1)
    therefore X^2 follow chi square distribution with 1 degree of freedom , thus Y follows chi square with 50 degrees of freedom (since Xi's are independent)
    and we know that mean of chi square distribution is 2K(where K is the degree of freedom)
    thus Var(Y)=100
    and E(Y^2)=100+50^2=2600
     
    divyam sankharva, Apr 28, 2015
    #3
  4. vidhya36

    vidhya36 Very Active Member

    It follows chi - square 50 distribution.
     
    vidhya36, Apr 29, 2015
    #4

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