4: Use the Product Rule (Lecture 2) to answer the first three of these questions (the last one may need something extra). Suppose we have a set of n air travellers called p1, . . . , pn. They've just landed at Pearson International Airport and they get off the plane one at a time with p1 getting off first, followed by p2, and so on, up to pn. The arrival hall at the airport has three queues, Q1, . . . , Q3 and they're all empty when the air travellers arrive. The customs agents are on their break, so all passengers have time to choose a queue before any passenger gets to leave. 2 1. The travellers come from England and walk calmly through the corridor from the plane to the arrival hall and arrive in the same order they got off the plane. In this way, their order within each queue matches the order they got off the plane. How many ways are there to assign the travellers to queues