申論題

Problem 7. (2.5 %) Consider two random variables X and Y, each taking val- ues in {1,2,3}. Let their joint PMF be such that for any 1 ≤ x, y  ≤ 3,

Then, 

(i) X and Y can be independent or dependent depending upon the strictly positive values
(ii) X and Y are always independent
(iii) X and Y can never be independent