1. The problem statement, all variables and given/known data Discrete random variables X and Y , whose values are positive integers, have the joint probability mass function pXY(x,y) = 2-x-y. Determine the marginal probability mass functions pX(x) and pY(y). Are X and Y independent? Determine E[X], E[Y], and E[XY]. 2. Relevant equations Independence is determined by whether p(x,y) = p(x)p(y) for all x and y. 3. The attempt at a solution My notes don't have much on the topic of determining marginal PMF's using a JPMF... I was hoping someone could point me in the right direction.