A train arrives at a station and waits 2 min before departing. Another train arrives at the station 18 minutes later, repeating the cycle. Identify the probability that a train will be at the station when you arrive. HELP PLEASE!!!

Answer: If the second train arrives at the station 18 minutes after the first one DEPARTS, then there's a train waiting at the station for 2 minutes out of every 20.
So the probability a train will be there when you arrive is
2/20 = 0.1