[pjdemers]

I got the problem wrong because I didn't know he never opens the door picked nor a door with a prize behind it. That's because I hadn't seen the show since I was about 5 years old, because that's about the time I stopped watching daytime TV.

[bemusedthrow75]

That is also in the problem description. Again, it doesn't matter whether he does or doesn't ever do it (though no game show host would ruin the game).

It is the described problem that matters.

There was so, so much writing like this at the time, people saying "well, if...".