The joint probability distribution function of random variables X and Y is given as p(x, y) = =y(2y - x), x = -1,0,1; y =1,2 a) Verify that p(x, y) is the joint probability distribution function. [3 Marks] b) Find the marginal distribution function of X and Y. [5 Marks] c) Obtain Cov(X, Y). Hence, are the variables independent? [10 Marks] d) Evaluate Var (X - Y). [10 Marks] Suppose that the random variables X and Y have joint probability density function given by f(x,y) = zxy; x Y). [3 Marks]