Let X and Y be random variables that have the joint probability density function (pdf)
f_{X,Y}(x,y) = { c(x+y) for 0 ≤ x ≤ 1, 0 ≤ y ≤ 1; 0 otherwise.
(a) Find the value of the constant c that makes the function f_{X,Y}(x,y) a valid joint pdf.
(b) Find the marginal probability PDFs of both X and of Y.
(c) What is P(X > Y | X < 1/2)?
(d) Find f_Y(y|x), the conditional probability distribution of Y given X = x.