4. X and Y are random variables with a joint distribution given below:
0
X=r
2
4
Y y 0 0.05 0.10 0.25
2 0.20 0.15 0.25
(a) Obtain the marginal distributions of X and Y.
(4 marks)
(b) Evaluate E(X), Var(X), E(Y) and Var(Y).
(4 marks)
(c) Obtain the conditional distributions of Y X = 2 and X/Y = 2.
(4 marks)
(d) Evaluate E(XY), Cov(X, Y) and Corr(X, Y).
(5 marks)
(e) Are X and Y independent? Justify your answer.
(3 marks)