題組內容

1. (5% each, totally 20%) Let X and Y be random variables, with the joint PMF: $$P_{X,Y}(x,y) = \begin{cases} c & \text{if } (x,y) = (1,1), (1,2), (2,1), (2,2); \\ 0 & \text{else}, \end{cases}$$ where c is a constant.

(d) What is the CDF of \( W \)?