Hey, i'm having a little trouble transitioning from single variable probability distributions to bivariate distributions, I'm just wondering if any of you guys have a minute to look over my solution to a question to make sure i'm not going astray on the foundation?

Thanks for your help!

So for we need to find .For the given Joint Probability Mass Function over the nine points with and , Determine and

From here,

Now onto the variance;

Have I gone horribly wrong somewhere? Or does this look like the appropriate approach? Thanks for helping me understand this!

Kasper