Two fifty foot ropes are suspended from a forty foot ceiling, about twenty feet apart.
Armed with only a knife, how much of the rope can you steal?
(In reply to
all of it! by Kyle)
I think you are the most correct. Regardless of how the ropes are attached to the ceiling, you still have enough rope to double it, pass it through an anchored point on (or near) the ceiling, and pull all the rope down.
Even if the ropes are embedded in a smooth ceiling, you can get away with stealing all but about a foot of rope. After cutting off the entire first rope, use a little bit of rope to make a loop with a tail. Tie the ends of the 50-foot ropes together and climb the second rope as you described. Then tie the tail of the loop to the very top of the fixed rope. Pass the long rope through and hold onto it as you described. Then cut the fixed rope just below where the loop is tied, slide down and take your 99 feet of rope.