>Why is that? The explanation is actually trivial: no matter how well things work, there is an absolute minimum time required to get to the airport. On the othe

>Why is that? The explanation is actually trivial: no matter how well things work, there is an absolute minimum time required to get to the airport. On the other hand, there are many things that might delay your trip: heavy traffic, closed roads, accidents... Perhaps an easier explanation is that within driving the course you will encounter several Poisson processes, and the waiting time for a Poisson process is an exponential distribution.