I am given the following joint distribution of two random variables X and Y:
$$ f(x,y)=2y \\ 0<y<1, 0<x<y $$
Now I need to find the marginal PDF of X but how do I select the limits? I am really confused. What is the general method for selection of limits?
self-study
tag and read its wiki. Here are some hints: 1) Draw $0 < y < 1$ in the $xy$-plane. 2) Draw $x = y$. 3) Where is the $x$-coordinate smaller than $y$-coordinate? $\endgroup$