The problem is better explained with a picture. PMF table:

Let X and Y be two random variables, whose joint PMF px,y (@, y) is given by the following table: x=1 1/4 1/8 x =0 1/8 1/2 y =0 y =1 So for example, px,y (0, 0) = 1/8; px,y (1, 0) = 1/4. Using this table, evaluate the following quantities. 1 . px ( 1 ) . Px (1) = 2. PXY (110). PX|y (1|0) = 3. PXA (1), where A = {Y2 > 0}. PXIA (1) =