A room without windows contains a door without any windows and inside is a light bulb on the
ceiling. There are no light switches inside the room. On the outside of the room are three
switches. Your task is to figure out which one of the three switches controls the light bulb. You
may change the light switches from on to off as often as you want, but when you do you
CANNOT see in the room because the door must be shut! You can only change the switches
when you are OUTSIDE the room and when the door is SHUT! You may enter the room only
once but you must close the door after you enter and again when you leave. There is a ladder in
the room as well. You cannot see through any cracks in the door. How would you figure out
which switch controls the light bulb?
Solution
press switch 1 for 2 minutes
then press switch 2
now
go inside room which bulb glows switch 2 represetn that
now
tocuh other two bulbs
which bulb is hotter thet represents switch 1
remaining bulb represnets switch 3