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Topic: How can he cross the bridge? (Read 584 times) |
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DeMark
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How can he cross the bridge?
« on: Mar 12th, 2004, 11:21am » |
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There is a bridge. By running, it takes 10 minutes to cross it. In the middle of the bridge there is a sentry box (this sounds weird to me. I found the word in a dictionary  ) and a guard.
A man wants to cross the bridge, but the guard lets nobody over. If you arrive to the middle of the bridge, guard will send you back to where you came from.
But, our man knows that the guard goes to sleep every 10 minutes and then sleeps for 5-6 minutes. When he wakes up, he goes to check is there someone trying to pass by.
How is the man going to get to the other side of the bridge?
P.S. I think this one fits better to Easy than to What happened, so I put it here.
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John_Gaughan
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Re: How can he cross the bridge?
« Reply #1 on: Mar 12th, 2004, 11:56am » |
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on Mar 12th, 2004, 11:21am, DeMark wrote:| There is a bridge. By running, it takes 10 minutes to cross it. In the middle of the bridge there is a sentry box (this sounds weird to me. I found the word in a dictionary ) and a guard. |
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I think that is almost what you are looking for. "Guard shack" is probably what you mean.
Anyway, I think this riddle is already on this site, but instead of 5-6 minutes it is just 6 minutes, and it is a woman trying to run across a bridge to escape the Nazis or Soviets or something.
The solution is trivial once you realize something :: the guard does not know where the man came from, only what side of the guard shack he is on. If he waits until the guard goes to sleep and then jumps out and runs across the bridge, he can make it just past the guard shack before he wakes up again. The guard will send him back to where he thinks he came from, which is the other side of the bridge from where he started. ::
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rmsgrey
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Re: How can he cross the bridge?
« Reply #2 on: Mar 12th, 2004, 12:47pm » |
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Warning - this post consists largely of quibbling. Since the quibble gives away the answer, I'm hiding it.
::
the problem statement explicitly says "If you arrive to the middle of the bridge, guard will send you back to where you came from" rather than "turn you around and march you off the bridge" or similar. We can deduce from this that the guard has a mysterious ability to tell which side you came from (maybe you leave muddy footprints?) so turning round halfway isn't going to fool him...
::
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John_Gaughan
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Re: How can he cross the bridge?
« Reply #3 on: Mar 14th, 2004, 8:32pm » |
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Quibble quibble quibble...
The man crawls underneath the bridge along the struts. Or he swims across the river below. Or he walks along the road below. Or...
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DeMark
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Re: How can he cross the bridge?
« Reply #4 on: Mar 15th, 2004, 11:29am » |
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Okay. This topic is closed. Another one?
There was a man, blind from the day he was born. He found out that in China there is a specialist who can give him his sight by surgery. (ummm... a mixed-up sentence. But you know what I want to say. Do you? )
Anyway, he and his brother travelled to China (by plane), he had a surgery and finally he was able to see. He was sooo happy he decided to went back by train so he can see more. He asked his brother to talk about things, to explain what is this & what is that.
But, in the middle of the trip he took his gun and shot himself.
Why?
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towr
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Re: How can he cross the bridge?
« Reply #5 on: Mar 15th, 2004, 11:48am » |
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::the train went through a tunnel, it was dark, he thought he was blind, so he killed himself due to lack of sanity..
both these are somewhere on the site though, else I wouldn't know the latter..::
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