Set the first switch on for about 10 minutes, and then switch on the second switch and then enter the room.
Three cases are possible:
1.Bulb is on => second switch is the answer
2.Bulb is off and on touching bulb , you will find bulb to be warm
=>1st switch is the answer
3.Bulb is off and on touching second bulb , you will find bulb to be normal (not warm)
=>3rd bulb is the answer