Results 1 to 2 of 2

Math Help - Moments part 2 - basics

  1. #1
    Junior Member
    Joined
    Sep 2012
    From
    Due North
    Posts
    26

    Moments part 2 - basics

    Given
    Mx(t) = exp(t^2 + 2t)
    My(t) = exp(3t^2 + t)

    Find the mgf of X + 2Y.
    ___________________________
    Can anybody explain how
    My(2t) = exp(12t^2 + 2t) ???? I figured this going backwards from the answer...so it may be wrong...

    THANKS
    ____________
    The answer is exp(13t^2 + 4t)
    Last edited by TheCountador; September 17th 2012 at 08:01 AM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor harish21's Avatar
    Joined
    Feb 2010
    From
    Dirty South
    Posts
    1,036
    Thanks
    10

    Re: Moments part 2 - basics

    Quote Originally Posted by TheCountador View Post
    Given
    Mx(t) = exp(t^2 + 2t)
    My(t) = exp(3t^2 + t)

    Find the mgf of X + 2Y.
    ___________________________
    Can anybody explain how
    My(2t) = exp(12t^2 + 2t) ???? I figured this going backwards from the answer...so it may be wrong...

    THANKS
    ____________
    The answer is exp(13t^2 =4t) that should be a + instead of an = sign
    E[e^{t(X+2Y)}]=E[e^{tX+2tY}]=E[e^{tX}]E[e^{(2t)Y}]=e^{[t^2+2t]}\times e^{[3(2t)^2+(2t)]}=...
    Last edited by harish21; September 17th 2012 at 07:43 AM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 25
    Last Post: January 15th 2010, 03:53 AM
  2. Sum of a part arithmatic and part geometric sequence
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: October 25th 2009, 10:53 PM
  3. The basics
    Posted in the Calculus Forum
    Replies: 7
    Last Post: April 5th 2009, 05:50 AM
  4. Replies: 14
    Last Post: February 13th 2009, 04:27 AM
  5. need help...forgotten the basics
    Posted in the Calculus Forum
    Replies: 3
    Last Post: May 29th 2007, 06:27 PM

Search Tags


/mathhelpforum @mathhelpforum