Answers like this always depend on the "rules". I'm reminded of the great Monte Hall puzzle, in which you are shown three doors, one of which is a grand prize and the other two are goats. After you choose one door, Monte reveals another door has a goat behind it. Then he asks you if you want to change your choice to the remaining door. Is there a reason to do it?

Depending on the "rules" governing what Monte does, the chance of the new door being the grand prize will either be 1/2 or 2/3. It's pointless to argue about which is correct until you know Monte's rules. (And given the way Monte normally works, the rules indicate the answer will be 2/3).