There is a room with a door (closed) and three light bulbs. Outside the room there are three switches, connected to the bulbs. You may manipulate the switches as you wish, but once you open the door you can't change them. Identify each switch with its bulb.

• Turn on a switch and leave it for some ten minutes. Turn it off, turn a second one on and open the door and go into the room. The glowing bulb corresponds to second switch. The bulb that is hot corresponds to first switch, as it was turned on for ten minutes and have heated up. The cold and not-glowing bulb corresponds to the third switch
• 15 years agoHelpfull: Yes(39) No(2)
• Turn first switch on for a few minutes. Then turn it off, immediately turn second switch on and immediately open the door and go into the room. The glowing bulb corresponds to second switch(presently on). The hot bulb belongs to switch one(just turned off) as it got heated while it was switched on. The cold bulb belongs to third switch(yet to be turned on).
• 15 years agoHelpfull: Yes(9) No(1)