Hello,
Actually, we have
So we have :
But is "counted" i times.
So it's actually
Here's the pmf:
I got the first part, which is verifying that this is a legitimate joint pmf, however I am stuck on finding the marginal pmf. I know that marginal pmf of X would be:
But wouldn't that just be in this case? But somehow I don't think it's that easy.
A striking similarity to the question in this thread: http://www.mathhelpforum.com/math-he...tml#post373172