4. Let f be the function of two variables
k(2-y ify<x<2andx,y>0
0
else
(a) Sketch the region where f > 0, and find the constant k so that f is a joint probability distribution. b) Find the probability that Y > 1. Sketch the region corresponding to this event.
(c) Find the probability that X + Y > 1. Sketch the region corresponding to this event.