Hi all! This is an interesting problem, on probability, for those who likes solving such things (like me ): A crowd of 100 passengers is awaiting departure in the airport. As it usually happens, each passenger has his own ticket for a certain place in the plane. As it also sometimes happens, there is an old mad woman ( ) among the passengers, which also has her own ticket. When the voice from the loudspeker, claiming the start of boarding, reaches her ears, she immediately rushes into the plane and takes a random seat. Other 99 passengers are assumed to be normal, polite people. They enter the plane one by one, and act in the following manner: if, entered the plane, one sees his real seat (that printed in the ticket) is free - he takes it. If his real place is already busy - he takes any of currently free seats... Question: What is the probability of that the 100th passenger will take his own place (that printed in his ticket)?