Can you solve this math problem?

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Re: Can you solve this math problem?

Post by sanddbox on Mon Sep 13, 2010 11:42 pm
([msg=45700]see Re: Can you solve this math problem?[/msg])

NerdyTB wrote:
sanddbox wrote:
NerdyTB wrote:I have a riddle that's math related. You have two pieces of string, each of which take an hour to burn from end to end. Using these two pieces of string, measure 45 minutes.


Divide the strings into fourths and burn three of the fourths? I don't really get what's complicated. You could also break out the boyscout skillz and tie a knot such that one fourth of one of the strings would overlap another (although I don't know if that would cause it to burn slower).

Do you have to use both of the strings?


The strings don't burn evenly and you do have to use both strings.


Ah, so they're not uniform length?
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Re: Can you solve this math problem?

Post by NerdyTB on Mon Sep 13, 2010 11:58 pm
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They can be the same length. They just burn faster and slower in some areas, like strings normally do.
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Re: Can you solve this math problem?

Post by sanddbox on Tue Sep 14, 2010 12:23 am
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Hmmm...light one on fire at both ends, and light the other on one end. When one string has completely burned and the other has gone 1/4 of the way, it's been 45 minutes.

Am I close?
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Re: Can you solve this math problem?

Post by NerdyTB on Tue Sep 14, 2010 12:28 am
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You're close, but not there yet. Remember, the strings don't burn evenly, so you can't judge by length or fractions.
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Re: Can you solve this math problem?

Post by sanddbox on Tue Sep 14, 2010 12:31 am
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NerdyTB wrote:You're close, but not there yet. Remember, the strings don't burn evenly, so you can't judge by length or fractions.


That's what I was worried about. What if you burn that string in the middle and the two ends instead of one end?
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Re: Can you solve this math problem?

Post by NerdyTB on Tue Sep 14, 2010 12:47 am
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You were closer on your last attempt. I'd say this attempt is half correct and your one before this one is 5/8 correct.
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Re: Can you solve this math problem?

Post by fashizzlepop on Tue Sep 14, 2010 8:10 pm
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NerdyTB wrote:You were closer on your last attempt. I'd say this attempt is half correct and your one before this one is 5/8 correct.

You said we can't use fractions! lol.

Light both ends of the first and one of the second. Then once the first is all used up, light the last end of the second...? Bazzinga.
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Re: Can you solve this math problem?

Post by NerdyTB on Tue Sep 14, 2010 8:16 pm
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fashizzlepop wrote:
NerdyTB wrote:You were closer on your last attempt. I'd say this attempt is half correct and your one before this one is 5/8 correct.

You said we can't use fractions! lol.

Light both ends of the first and one of the second. Then once the first is all used up, light the last end of the second...? Bazzinga.

Very funny.

You did get it correct however. Since the time it takes the first one to burn up is 30 minutes because you lit both ends, you know the time left on the remaining one is 30 minutes. Lighting the second end would cut that time in half (lol another fraction), making it so when the second one burns up, 45 minutes would have passed.
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Re: Can you solve this math problem?

Post by fashizzlepop on Tue Sep 14, 2010 10:14 pm
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Credit to sanddbox for planting the seed.
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Re: Can you solve this math problem?

Post by sanddbox on Tue Sep 14, 2010 10:25 pm
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fashizzlepop wrote:Credit to sanddbox for planting the seed.


Oh, exploitable...
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