Suppose the die is tossed. we introduce two random variables x and y . let x equal 1 if the result is greater than 3 and 0 otherwise. (a). let y equal 1 if the result is odd and 0 otherwise. (b) find the joint probability mass function of x and y . (c) are the random variables x and y independent? justify your answer. (d) compute erx2 ? y s.