Question 3 [18 points] The contigency table of two discrete random variables X and Y is as follows. With P(X = 1 and Y = 1) = a, P(X = 1 and Y = 2) = 0.3, etc. b It is also given that E [X + Y] = 3. (a) What's the value of a and b? [12 points] (b) Calculate the expected value of the product: E [X Y]. [6 points]