Suppose the joint pdf of lifetimes of a certain part and a spare is given by
f(x, y) = e^?(x+y), 0 < x < ?, 0 < y < ?
and zero otherwise.
(a) Find the marginal pdf of X?
(b) Find P(X > 2)?
(c) Find P(X < Y ).
(d) Find P(X + Y ) > 2
(e) Are X and Y independent?