EPT[Math Puzzle] Day[9] - Page 2
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igotmyown
United States4291 Posts
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DeathSpank
United States1029 Posts
ugh... the only way to do it would be to start at a speed of say 1 and shoot until you would have hit it if it was going at that speed...then switch to 2...then do it again...and keep calculating....and assuming you don't know which way its gone you have to alternate between negative and positive speeds....fucking flee....as a computer scientist who likes efficiency these types of problems make me want to die. | ||
Kau
Canada3500 Posts
Shoot point 1 at second 1, if its speed was 1 it dies. Shoot point 4 at second 2, if its speed was 2 it dies. Shoot point 9 at second 3, if its speed was 3 it dies. So I guess shoot at every (time)^2 point and it will eventually die, but how would you do both directions  Edit: Idea? Shoot point 1 at second 1, if its speed was 1 it dies. Shoot point -2 at second 2, if its speed was -1 it dies. Shoot point 6 at second 3, if its speed was 2 it dies. Shoot point -8 at second 4, if its speed was -2 it dies. and I guess cover all the speeds up to infinity? | ||
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FragKrag
United States11552 Posts
On May 10 2009 12:31 LosingID8 wrote: true true, i just assume all engineers are super good at all kinds of math  If engineers were great at all kinds of math, why would they need mathematicians? :p | ||
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Kau
Canada3500 Posts
On May 10 2009 15:43 FragKrag wrote: If engineers were great at all kinds of math, why would they need mathematicians? :p To put them in their place ![[image loading]](http://imgs.xkcd.com/comics/purity.png) | ||
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evanthebouncy!
United States12796 Posts
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Monoxide
Canada1190 Posts
On May 10 2009 09:56 aznmathfreak wrote: + Show Spoiler + Let's say that the flea is traveling at the speed of x. On turn one, it can either be at x or -x depending on which direction it chose to travel in. On turn two, it can be at 2x or -2x. Since we don't know x, but we do know that its domain is the natural number, we can take turns shooting at each one of those natural number. IE, one turn one, let's guess that x is 1 in the positive direction, and since it's turn one, it would have gone 1x1 in the positive direction. Second turn, let's change our assumptions and guess that x is still 1 but in the negative direction. Since it's now turn two, we will have to fire 2x1 in the negative direction, or -2. With this method, you will eventually reach x high enough that you have guessed what was the speed of the flea, therefore hitting him/it. Edit: ShadowDrgn's got it, the expression is on turn n, you shoot at (-1)^(n+1) x ceiling of (n/2) x n this is correct... dam why am i soo slow on looking at these.. by the time I look at them they're already answered | ||
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evanthebouncy!
United States12796 Posts
On May 10 2009 20:10 Monoxide wrote: this is correct... dam why am i soo slow on looking at these.. by the time I look at them they're already answered Lol nothing wrong with that, I titled it day[9] and he hasn't found out about it at all :p | ||
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snowbird
Germany2044 Posts
![[image loading]](http://i42.tinypic.com/1zyucfo.png) just to put the mathematicians in their place | ||
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Monoxide
Canada1190 Posts
On May 10 2009 20:33 evanthebouncy! wrote: Lol nothing wrong with that, I titled it day[9] and he hasn't found out about it at all :p who were u trying to hide it from? | ||
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kernipu
Germany193 Posts
![[image loading]](http://img13.imageshack.us/my.php?image=math9.jpg) | ||
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edahl
Norway483 Posts
Hmmh, the speed is a multiple of 2 or 3, and 1. The flea's possible motion at a given speed corresponds to a cyclic group of infinite order. If the group is addition on 2nZ, the flea is exclusively restricted to even numbers, as 2|2nm. Else, the flea will shift between even and uneven numbers. Anyway, I'd just shoot randomly at even numbers all across the numberline :-P It doesn't bring me much closer to a solution, but I don't have time due to final exams tuesday. But I thought I'd show I look at your quiz ^^ | ||
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evanthebouncy!
United States12796 Posts
On May 11 2009 06:54 edahl wrote: + Show Spoiler + Hmmh, the speed is a multiple of 2 or 3, and 1. The flea's possible motion at a given speed corresponds to a cyclic group of infinite order. If the group is addition on 2nZ, the flea is exclusively restricted to even numbers, as 2|2nm. Else, the flea will shift between even and uneven numbers. Anyway, I'd just shoot randomly at even numbers all across the numberline :-P It doesn't bring me much closer to a solution, but I don't have time due to final exams tuesday. But I thought I'd show I look at your quiz ^^ ha :D thx thx | ||
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