Railway track allocation. Refer to the Journal of Transportation Engineering (May 2013) investigation of railroad track allocation at a railway station with 11 tracks, Exercise 2.16

(p. 68). A simple algorithm designed to minimize waiting time and bottlenecks is one in which engineers randomly assign one of the 11 tracks to a train entering the station.

a. What is the probability that track #7 is assigned to an entering train?

b. Unknown to the engineer, tracks #2, #5, and #10 will have maintenance problems. What is the probability that one of these problematic tracks is assigned to an entering train?