A country has exactly 10 major cities. The government is adding ights between pairs of cities.

Suppose the funding allows for exactly 18 bidirectional ights to be added. What is the probability that

city A and city B are connected by a ight? What is the probability that one can ight city A to city

B to city C? (each a direct ight). What is the expected number of ights out of city A? Suppose now

that exactly 5 of those cities apply a tax at their airport. What is the probability that there are exactly 6

ights for which the tax is applied?