Results 1 to 2 of 2

Math Help - Joint Probability Density Function with Two Continuous Random Variables

  1. #1
    Junior Member
    Joined
    Dec 2007
    Posts
    32

    Joint Probability Density Function with Two Continuous Random Variables

    Hi

    Each front tire on a vehicle is supposed to be at a pressure of 26 psi. Suppose the actual air pressure is a rv in each tire: let x = right and y = left, with the joint pdf:

    f(x,y) = K(x^2+y^2) 20<= x <= 30, 20<= y <= 30
    0 otherwise

    What is the value of K?

    So the formula is the

    double integral from 20 to 30 [k(x^2+y^2) dxdy

    I solved it to get (2k * (38000/3)) , but to my surprise the solution showed this answer multiplied by 10.

    Can anyone explain to me why I need to multiply by ten?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Aug 2007
    From
    USA
    Posts
    3,111
    Thanks
    2
    What you have, 2k*38000/3, is one fifth (1/5) the value of the integral. You should do that again and be more careful.

    I do not understand why the solution would be in this form. It asks for K. You should have to solve the value of the integral "= 1" in order to find K.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Joint density function of X(discrete) and Y(continuous)?
    Posted in the Advanced Statistics Forum
    Replies: 7
    Last Post: January 23rd 2011, 12:58 AM
  2. Replies: 1
    Last Post: November 2nd 2010, 07:25 PM
  3. Replies: 1
    Last Post: September 3rd 2010, 10:51 PM
  4. a continuous random variable with probability density function
    Posted in the Advanced Statistics Forum
    Replies: 7
    Last Post: December 5th 2009, 09:15 AM
  5. Replies: 10
    Last Post: November 6th 2008, 02:17 AM

Search Tags


/mathhelpforum @mathhelpforum