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14 replies to this topic

#1 TOPHAT

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Posted 27 March 2008 - 02:05 PM

If you're 8 feet away from a door and with each move you advance half the distance to the door.

How many moves will it take to reach the door?
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#2 Lost in space

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Posted 27 March 2008 - 02:19 PM

If you're 8 feet away from a door and with each move you advance half the distance to the door.

How many moves will it take to reach the door?

Never can reach the door - there will always be a half to infinity!
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#3 Theo

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Posted 27 March 2008 - 03:58 PM

Never can reach the door - there will always be a half to infinity!


i heard a very similar one to this in school. " The moon is 384,400km away. The space ship you are traveling in can reach a top speed of 8,400kph. If the space ship you are in traveled half the distance to the moon every day, how long will it take you to get there?"

Both answers are the same. But even when the answer was given to the class, "You will never reach the moon, you will always be halfway there", students still needed some explination.
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#4 statman

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Posted 27 March 2008 - 04:24 PM

If you're 8 feet away from a door and with each move you advance half the distance to the door.

How many moves will it take to reach the door?

Spoiler for Defime reach

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#5 itachi-san

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Posted 27 March 2008 - 07:56 PM

I get the point of the riddle, but looking at it a bit differently, it will take until you arrive at arm's length to reach the door.
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#6 ash013

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Posted 27 March 2008 - 08:48 PM

If you're 8 feet away from a door and with each move you advance half the distance to the door.

How many moves will it take to reach the door?

NEVER...
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#7 Noct

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Posted 27 March 2008 - 09:21 PM

But add a twist:

Can you explain how you get anywhere then? If I'm at work and I want to go to my house 10 miles away, how will I ever get there? First I must go half, and then half of the remaining, and then half of the remaining...

How do I get anywhere?
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#8 itachi-san

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Posted 27 March 2008 - 09:23 PM

But add a twist:

Can you explain how you get anywhere then? If I'm at work and I want to go to my house 10 miles away, how will I ever get there? First I must go half, and then half of the remaining, and then half of the remaining...

How do I get anywhere?



You get anywhere by not following the logic of only moving a half the distance at a time. If your house is 10 miles away, then travel 10 miles.
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#9 Noct

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Posted 27 March 2008 - 09:27 PM

You get anywhere by not following the logic of only moving a half the distance at a time. If your house is 10 miles away, then travel 10 miles.


But to travel 10 miles I first have to travel 5. And then to travel the remaining 5 miles I first have to travel 2.5 miles. And to travel the remaining 2.5 miles I first must travel 1.25 miles... etc. etc.

So I still shouldn't be able to get anywhere
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#10 itachi-san

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Posted 27 March 2008 - 09:36 PM

But to travel 10 miles I first have to travel 5. And then to travel the remaining 5 miles I first have to travel 2.5 miles. And to travel the remaining 2.5 miles I first must travel 1.25 miles... etc. etc.

So I still shouldn't be able to get anywhere



Why can't you say to travel 10 miles you first need to travel 7? 1? or 10?
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