Suppose that each of the 30 points of the sample space of Exercise 2.40 is assigned the probability 1/30. Find the probabilities that at a given moment
(a) At least one of the station wagons is empty;
(b) Each of the two station wagons carries the same number of passengers;
(c) The larger station wagon carries more passengers than the smaller station wagon;
(d) Together they carry at least six passengers.