Married Puzzle

Many people say “cannot be determined” at first because Anne’s marital status is unknown. But if you think about it for longer, you realize that the answer is “yes.” Imagining a longer chain of people can help: you only know that the first person is married and the last person is unmarried, and you know nothing about anyone in the middle. Even then, as you move along the chain from the married person at the start to the unmarried person at the end, you are guaranteed to pass a “flip” from married to unmarried at some point. We can’t say where it happens (or, in this case, how many times it happens), but we can say that it does happen.