06-23-2010, 12:59 PM | #1 |
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Fuse Timer Puzzle
This one's adapted from http://www.rinkworks.com/brainfood/p/discrete5.shtml
You like your boiled eggs to be boiled for exactly three-and-a-half minutes. Unfortunately, you've broken your three-and-a-half minute egg timer, and the only other timing mechanism in the house are some slow-burning four minute fuses*. NB. I mean fuses that burn for exactly four minutes, not four fuses that burn for a minute each! Unfortunately (again), you know that the fuses do not burn at a uniform rate, so you can't just cut one of them to a three-and-half minute length. Can you time exactly three-and-a-half minutes for your egg using the four minute fuses? If so, how? Oh - and spoiler tags around answers please. Many thanks to all of you who remembered without me reminding you. *No, I don't know why you have four-minute fuses in the house either. And yes, you do have some matches as well. Last edited by pdurrant; 06-23-2010 at 02:12 PM. Reason: Forgot the spoiler tags reminder |
06-23-2010, 01:33 PM | #2 |
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Spoiler:
I'd probably end up contacting the Chinese manufacturer of these timing fuses to figure out what math they used to calculate these non-uniform fuses' burn times. |
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06-23-2010, 01:35 PM | #3 |
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06-23-2010, 01:40 PM | #4 |
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06-23-2010, 01:41 PM | #5 |
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Okay, after looking at this for some time thinking it can't be possible, or that I'm missing some special physics of fuses , here's my idea:
Spoiler:
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06-23-2010, 01:44 PM | #6 |
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06-23-2010, 01:46 PM | #7 |
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06-23-2010, 02:13 PM | #8 |
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Sorry, the fuses each burn for four minutes, not one minute. Question changed to emphasise that each individual fuse burns for four minutes.
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06-23-2010, 02:14 PM | #9 |
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06-23-2010, 02:15 PM | #10 |
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06-23-2010, 05:32 PM | #11 |
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Am I along the right path?
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06-23-2010, 05:34 PM | #12 |
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I sure hope we have an unlimited supply of fuses, because I keep lighting them as I play with how to time subsequent burn rates.
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06-23-2010, 05:35 PM | #13 |
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06-23-2010, 05:42 PM | #14 |
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06-24-2010, 04:13 AM | #15 |
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I couldn't figure this one out. I was able to start, but once again was lost.
Spoiler:
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