# Marginal PDFs

• Mar 11th 2009, 10:03 PM
ah-bee
Marginal PDFs
How would i find the marginal pdfs for this function
[f, XY] (x, y) = 2, y <= x <= 1 , 0 <= y <= 1
0, otherwise

What integration limits would i take for the marginal pdf of X say, between y and 1? or 0 and 1. Same thing goes for marginal pdf of Y.

Thanks
• Mar 11th 2009, 11:35 PM
Moo
Hello,
Quote:

Originally Posted by ah-bee
How would i find the marginal pdfs for this function
[f, XY] (x, y) = 2, y <= x <= 1 , 0 <= y <= 1
0, otherwise

What integration limits would i take for the marginal pdf of X say, between y and 1? or 0 and 1. Same thing goes for marginal pdf of Y.

Thanks

If you want the marginal pdf of X, then you have to integrate with respect to y. And the boundaries for y are 0 to x (since x<=1)
For the marginal pdf of Y, you have to integrate with respect to x, which indeed goes from y to 1.
• Mar 12th 2009, 12:09 AM
matheagle
See
http://www.mathhelpforum.com/math-he...ectations.html
There the y is bigger than x, but all you need to do is switch the variables.