For each case, list the values of X and f(x) and examine if the specification represents a probability distribution. If it does not, state what properties are violated.
(a) f(x) = 1/6(x - 1) for x = 1, 2, 3, 4
(b) f{x) = 1/3(x - 3) for x = 2, 3, 4, 5
(c) f(x) = 8/15 1/2x for x = 0, 1, 2, 3