Lost Boarding Pass

There are 100 passengers which are trying to get on a plane. The first passenger, however, has lost his boarding pass, so decides to sit on an arbitrary seat. Each successive passenger either sits on his own seat if it is empty or on an arbitrary other if it is taken. What is the chance that the last person will sit in his own seat?

SOLUTION

The chance is 50%. Indeed, the last passenger will either have to sit in his own seat or the one which belongs to the first passenger. Since there hasn’t been any preference made by anyone at any time towards any of these two seats, the probability that either of them is left last is 1/2.

Puzzle Prime

Puzzle Master at Puzzle Prime | Website

Puzzle Prime is tirelessly looking all around the internet to find the very best puzzles and bring them all to puzzleprime.com.

Puzzle Prime

Puzzle Newsletter