A bowl contains 20 chips, of which 9 are red, 8 are white and 3 are blue. Six chips are taken at random and without replacement. Find the probability that
(a) each of the 6 chips is red;
(b) there are 3 red, 2 white and 1 blue chip among the six chips selected;
(c) none of the 6 chips selected is blue; and
(d) there is at least 1 white and at least 1 blue chip