Question 3:
If joing prob dist of X and Y is given by :
F(x,y) = x+y/30, x=0 1 2 3 , y=0 1 2
find P(X>Y)
Does it mean integrate from value 2 to 3 ?
You only integrate when the random variable is continuous. From what you posted, it's pretty obvious that X and Y are taking on discrete values and are therefore discrete random variables.
Pr(X > Y) = Pr(X = 1 and Y = 0) + Pr(X = 2 and Y = 0) + Pr(X = 2 and Y = 1) + ......