I'm posting one puzzle, riddle, math, or statistical problem a day. Try to answer each one and post your answers in the comments section. I'll post the answer the next day. Even if you have the same answer as someone else, feel free to put up your answer, too!
Monday, July 30, 2007
One smart thief
Two fifty foot ropes are suspended from a forty foot ceiling twenty feet apart. You have only a knife. How much of the rope can you steal?
I grab the bottom end of one rope, and holding it in my mouth, climb the other all the way to the top. From there, I reel in the dangly rope, so that I'm holding thirty feet of it, and there's twenty feet taught along the ceiling. Cut off the rope that's at the ceiling: it drops to the ground, almost fifty feet long. And then I release the stub and let myself swing.
Once the swinging comes to a rest, I'm twenty feet up in the air. I'd rather not jump from that height, but I certainly don't mind a ten-foot drop, if the floor isn't too bad --- hm, if the floor is dirt or smooth small stones, then ten feet is fine; if it's sprung wood, seven to ten; if it's tile on cement, I'd rather not drop more than four or five feet --- and so I climb down the rope until it's safe to jump, and cut off the end there.
So, all told, I definitely have a fifty-foot rope. And even without any jumping another ten feet (plus I'm six feet tall, and can reach up), and if jumping is ok, maybe twenty feet. But being conservative, 50 + 10 + 6 = 66 feet of rope.
It might be possible to grab just about all the rope (given you're penchant for acrobatics) and how well you can place the knife into the ceiling (there are other solutions to this problem, this is just an example).
Climb up the first rope, carrying the end of the other rope with you. Tie the second rope around your waist and cut the first rope off at the top. Swing down on the second rope.
Climb up to the top of the second rope and cut it nearly through. Stick the knife into the ceiling and tie the first rope onto it. Then climb down it 'fall' onto the second rope to break the remaining strands.
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Well, if I didn't mind some acrobatics:
ReplyDeleteI grab the bottom end of one rope, and holding it in my mouth, climb the other all the way to the top. From there, I reel in the dangly rope, so that I'm holding thirty feet of it, and there's twenty feet taught along the ceiling. Cut off the rope that's at the ceiling: it drops to the ground, almost fifty feet long. And then I release the stub and let myself swing.
Once the swinging comes to a rest, I'm twenty feet up in the air. I'd rather not jump from that height, but I certainly don't mind a ten-foot drop, if the floor isn't too bad --- hm, if the floor is dirt or smooth small stones, then ten feet is fine; if it's sprung wood, seven to ten; if it's tile on cement, I'd rather not drop more than four or five feet --- and so I climb down the rope until it's safe to jump, and cut off the end there.
So, all told, I definitely have a fifty-foot rope. And even without any jumping another ten feet (plus I'm six feet tall, and can reach up), and if jumping is ok, maybe twenty feet. But being conservative, 50 + 10 + 6 = 66 feet of rope.
It might be possible to grab just about all the rope (given you're penchant for acrobatics) and how well you can place the knife into the ceiling (there are other solutions to this problem, this is just an example).
ReplyDeleteClimb up the first rope, carrying the end of the other rope with you. Tie the second rope around your waist and cut the first rope off at the top. Swing down on the second rope.
Climb up to the top of the second rope and cut it nearly through. Stick the knife into the ceiling and tie the first rope onto it. Then climb down it 'fall' onto the second rope to break the remaining strands.