Random variables (probability)

1. Oct 30, 2015

TheMathNoob

1. The problem statement, all variables and given/known data
I have the joint cdf of two random variables X and Y and they ask me to find the cdf of just Y. I know that you just take the limit of the cdf as x->infinity, but I am just wondering if you can also do this by calculating the joint pdf and then the marginal of Y and then from the marginal of Y, the cdf of Y.

2. Relevant equations

3. The attempt at a solution

2. Oct 30, 2015

Ray Vickson

Yes, sometimes that is how it must be done. However, in your case that would be doing it the hard way, since taking the $x \to \infty$ limit is easier.

3. Oct 30, 2015

TheMathNoob

Thank you!!!!, I was so worried about that one in the test.