Question 1: A large domestic airport handles 90 take-offs per hour. For take-off, an aircraft leaves the gate, taxies for some distance and awaits its turn on the runway. Average time spent by an aircraft between leaving the gate and taking off is 12 minutes. Similarly, aircrafts spend average of 8 minutes between landing and reaching their gate. What is the average number of aircrafts on the runway at the airport?

In the above example, flights spend 1 hour at the gate between one arrival and the next departure. If the airport has 150 gates, what fraction of gates are occupied on average?