Beside a closed door to a room there are three light switches. Only one switch is for the light inside the room. You must find the correct switch to turn on the light before you enter the room. You can enter the room only once. All three switches can be in the up or down position for the light inside the room to come on. How can you tell if you have the right switch on for the light before entering the room?

Granpappy sez to peak under the door after trying each switch. I think he's pretty good at getting glances under doors, anyway.

I say - just open the door & don't 'enter' the room to see if the light is illuminated after trying each switch right beside the door...

Aha! Now you see, ol' Granpappy is smarter than people think he is. I do wish he would quit peeking under doors though.

Yep! I would open the door, too, Beetle, and enter only after I got the right switch.

won't know you got the correct switch unless you touch the hot bulb after trying a switch for a short period ... & then try the second one. If not hot or not on... then the last is your switch

....but, if the bulb is clear on the other side of the room?