100 people waiting to get onto the plane. You are last in line. Each person has a boarding pass with an assigned seat. The first person to board, drops his pass before he gets on and does not remember what seat that he was assigned so he randomly takes a seat. Each person boarding thereafter may or may not sit in their assigned seat. What are the odds that you will be able to sit in the seat assigned to you.
BTW, I do not know the answer, just trying to help a friend out.