Where I live most cars have 4 doors, but since we are expected to pretend this is a well-posed problem we must assume there are literally 3 doors at the game host location.
Evidently the participant entered through one of them and already knows whats behind one door. If he saw the car during entry, the correct choice would be the door of entry. The host can open (and close, and open, ...) doors with goats all day long, the participant would know the car is where he just saw it.
If the participant did not see the car during entry it must be behind one of the remaining doors: either behind the back door, or behind the emergency exit door.
Clearly it would be highly illegal to obstruct the emergency exit door with a car, so under Standard Assumptions (see assumption 42, the last one in the code) we can assume the host did not park the car behind this emergency exit door. Especially since emergency exit doors open outwards.
Hence the car was parked behind the remaining backdoor, and since this follows from the Standard Assumptions we can conclude the participant made the same (by definition valid assumption) as described here, since its a Standard Assumption, and assumption 1 of the Standard Assumptions is that in the absence of necessary knowledge, everyone makes the Standard Assumptions.
Given that the participant (using the standard assumptions) knew immediately which door hides the car and given that this door was his initial "guess", the correct solution (under Standard Assumptions) is to stay with the initial choice.
Evidently the participant entered through one of them and already knows whats behind one door. If he saw the car during entry, the correct choice would be the door of entry. The host can open (and close, and open, ...) doors with goats all day long, the participant would know the car is where he just saw it.
If the participant did not see the car during entry it must be behind one of the remaining doors: either behind the back door, or behind the emergency exit door.
Clearly it would be highly illegal to obstruct the emergency exit door with a car, so under Standard Assumptions (see assumption 42, the last one in the code) we can assume the host did not park the car behind this emergency exit door. Especially since emergency exit doors open outwards.
Hence the car was parked behind the remaining backdoor, and since this follows from the Standard Assumptions we can conclude the participant made the same (by definition valid assumption) as described here, since its a Standard Assumption, and assumption 1 of the Standard Assumptions is that in the absence of necessary knowledge, everyone makes the Standard Assumptions.
Given that the participant (using the standard assumptions) knew immediately which door hides the car and given that this door was his initial "guess", the correct solution (under Standard Assumptions) is to stay with the initial choice.