I've been struggling with this particular distribution. I'm told that and have a trinomial distribution with parameters , and
I know that the joint pmf is
I'm asked to find various things, such as
I don't want anyone to solve all of these.
However, if someone can show me how to find the expected value of either x or y, I would be able to figure out the rest.
I have an inkling that , but how would I find the marginal of ???
I'd appreciate any input!!