Can Two types of vehicle use the university central bus station: Uni-links and National Express coaches. a) On average, a National Express coach arrives every two hours. What is the probability that...

Can Two types of vehicle use the university central bus station: Uni-links and National Express coaches.
a) On average, a National Express coach arrives every two hours. What is the probability that only one bus will arrive in a four hour period?
b) On the U1 Uni-link bus route, buses either go to the airport or to the docks. Other Uni-link routes do not go to the airport. At the bus station, half of the U1 buses which arrive are going to the airport. At midday, 10% of the Uni-link buses are full. Of these particular buses, 30% are airport buses on the U1 route. U1 buses make up 40% of the Uni-link arrivals at the bus station. What is the probability that a bus is full at midday, given that it is an Airport U1 bus?
(I am not sure, Does this question use the conditional probability formula? )
c) Are the events ‘bus is full’ and ‘bus is going to the airport’ independent? Show your reasoning.