>>>>In one room, there are three switches. They control three lightbulbs in an adjoining room, but you don't know which switch controls which lightbulb. All switches are initially in the "off" position. You can't see the other room from where the switches are.
>>>>
>>>>Your task is to find out which switch controls which lightbulb. You can manipulate the switches all you want, and then go ONCE into the adjoining room to inspect the lightbulbs.
>>>
>>>
>>>Hmm.. Flip the first switch and leave it on for 60 seconds. Turn it off and flip the 2nd.
>>>Go into the room, note which light is on, feel for the hot bulb and you'd know which switches control which lights.
>>
>>Yes, that is the correct solution.
>
>But the setup is obsolete. All my bulbs are cold. I didn't even think of hot bulbs.

I always wonder what kids must think when their parents say "Oh look, there's a choo-choo". No kid today has seen (well, 99.9%) a steam engine in operation.
Same for the telephone "ringing".