[Litodude]

i was told this back in highschool, though i've changed it a bit.

you are stuck in a room.

this room has a door, and a transparent floating screen.

the room is metallic.

the door is metallic. 

the screen is intangible and unbreakable..

the knob is metallic, and has no significant features other than an engraving which signifies the direction in which the knob is to be turned. 

the hinges which the door turns upon, is on the other side, indicating the door is turned away from you.

you are given a lighter. this lighter is unbreakable, and immovable apart from its intended function: to light.

you are given four pieces of string. the pieces of string non-uniformly burn for 30 minutes each. 

you are given a 5x5 cm piece of cloth. the cloth is neatly folded and can fit in between the cracks of the door

you are given a pencil. it is sharpened and #2.

the floating screen indicates: "the door will only open after precisely 45 minutes of time elapses, no sooner, no more - otherwise you are electrocuted  upon twisting the knob. 

your body can only handle two electrocutions before dying. if you cannot exit within 2 hours you will be killed."

it then counts down: 5, 4, 3, 2, 1, GO.

how do you get out?

edit- grmamarrar