The probabilities that a service station will pump gas into 0, 1, 2, 3, 4, or 5 or more cars during a certain 30-minute period are 0.03, 0.18, 0.24, 0.28, 0.10, and 0.17, respectively, find the probability that in this 30-minute period
(a) More than 2 cars receive gas;
(b) At most 4 cars receive gas;
(c) 4 or more cars receive gas.