3-1.1 Two random variables have a joint PDF of fxy = 0 for x < 0 and y < 0, fxy = xy for 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1, and fxy = 1 for x > 1 and y > 1.
a) Find the joint and marginal PDFs.
b) Use fxy and find P(X ≤ 3/4, Y > 1/4), P(X = 3/4, Y = 1/4), and P(X ≤ 1/4).
3-1.2 Let fxy = kxy for 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1, and fxy = 0 elsewhere.
a) Find k.
b) Find the marginal PDFs.
c) Are X and Y independent?
d) Find P(X ≤ 1/2, Y > 1/2).