## Search found 209 matches

Wed Jun 20, 2007 3:50 pm UTC
Forum: Logic Puzzles
Topic: I dare you to solve this.
Replies: 82
Views: 36131
apeman5291 wrote:the first puzzle is kind of like this one:
http://math.cofc.edu/MATHMEET/truth-sprint.pdf

What tools were you allowed to use? I'll admit to using a list of the primes and a prime factor program.

Spoiler:
Part I:
2, 3, 8, 9

Part II:
R = {2893, 3289, 3982, 8239, 9328, 9823}
Wed Jun 20, 2007 3:33 pm UTC
Forum: Mathematics
Replies: 92
Views: 22737
LTPS wrote:Somehow I always say "62" in any sort of random-number scenario. I can't recall when or why it became my random number, or anything it might be of even mild relevance to.

62 is the first uninteresting number.
Tue Jun 19, 2007 2:51 pm UTC
Forum: Logic Puzzles
Topic: Lock Box solution
Replies: 29
Views: 7620

### Lock Box solution

Romeo and Juliet live on opposite sides of a war torn country. Romeo wants to send Juliet a ring. Unfortunately the mail is very corrupt and anything that is sent in the mail that is not in a locked box will be stolen. Both Romeo and Juliet have plenty of boxes and plenty of locks but no keys to ea...
Mon Jun 18, 2007 5:28 pm UTC
Forum: Mathematics
Replies: 92
Views: 22737
Seems a bit like the gambling theory "It didn't come up the last three hundred times it over due now". I always say that even though it's not really true. Because the probabilities are the same no matter what trial as long as everything else is kept constant. I am right, right? This is tr...
Fri Jun 15, 2007 10:23 pm UTC
Forum: Mathematics
Topic: irrational inches
Replies: 31
Views: 6154
tendays wrote:
Wow I must have been tired. Somehow I thought he was saying 2pi is circumference/radius. Anyway my point was that woxor's rod is not funky, and that still holds.

Having just read the 2 pi article in the favorite irrational number thread, this makes sense.
Fri Jun 15, 2007 5:41 pm UTC
Forum: Mathematics
Topic: irrational inches
Replies: 31
Views: 6154
"I need a rod one inch in diameter and pi inches around!" Could be fun playing with the new irrational measuring tape, if nothing else. that's one funky rod :shock: What's funky about it? :-) pi is circumference / radius so you just defined a rod half as big around as it should be No. (em...
Thu Jun 14, 2007 7:54 pm UTC
Forum: Mathematics
Topic: a number game
Replies: 21
Views: 4311
Well, just because some numbers don't can't win of others are picked, doens't necessarily mean there's a best single strategy. This is a bit like the lowest-unique-bid auction puzzle though. A best strategy for one person is the best strategy for everyone since the game is identical for all players...
Tue Jun 12, 2007 11:24 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 494906

What do you get when you cross a donkey with an elephant? A: DonkeyElephant sin ? This is a bad first post because 1. It's not in the introduction thread 2. The joke has been done already in this thread (in this page even) 3. You used obnoxiously large font Try again! 4. http://albinoblacksheep.com...
Tue Jun 12, 2007 11:19 pm UTC
Forum: Science
Topic: Why cant you go the speed of light with this method...?
Replies: 34
Views: 9276
Unless he just means that the fuel ejected by the small rocket will eventually hit the big rocket and push it backwards, which is true. Yes this is what I mean. 2 cases: 1) There is an atmosphere inside the mother rocket. The force of the mother rocket is applied by way of the atmosphere (mother ro...
Tue Jun 12, 2007 6:42 pm UTC
Forum: Mathematics
Replies: 92
Views: 22737
wouldn't you first think of the comen numbers, therefore you can't pick them because that wouldn't be random Nope. A truly random number would (probably) be "common" because a random selection of something is more likely to choose, well, the more likely thing. That's where probability com...
Tue Jun 12, 2007 6:10 pm UTC
Forum: Mathematics
Topic: Epsilon-Delta definition of limits.
Replies: 23
Views: 7197
Touche I guess I should have thought about that for a second before I replied. F***ing calculus books, why do they prove it the way the do then?
Tue Jun 12, 2007 5:18 pm UTC
Forum: Science
Topic: Why cant you go the speed of light with this method...?
Replies: 34
Views: 9276
Relativisitic effects aside, there's also a major flaw with this plan. Things accelerate by pushing off of other things and repelling them in the opposite direction (conservation of momentum). In the rocket's case, it is pushing off of fuel. If a large rocket were carrying a smaller rocket and the s...
Tue Jun 12, 2007 4:49 pm UTC
Forum: Mathematics
Topic: Epsilon-Delta definition of limits.
Replies: 23
Views: 7197
A minor detour. Well a large one, but the other day I was thinking about proving algebra of continous functions, particularly for multiplication of continous functions. I managed to come up with a scrappy proof which you had to set a delta to be a certain value if epsillon was less than 1, and diff...
Mon Jun 11, 2007 7:52 pm UTC
Forum: Computer Science
Topic: unary
Replies: 4
Views: 3772
Yes, that is how the peano axioms describe the natural numbers. However, do you consider the "end of a sequence" to be a seperate symbol or not? :) No, there is no seperate symbol for the end of sequence. So this means that the machine would basically be given as an input one of the natur...
Mon Jun 11, 2007 7:09 pm UTC
Forum: Computer Science
Topic: unary
Replies: 4
Views: 3772

### unary

In a book I am reading it uses the symbols 0 and 1 (in other words 2 symbols) as the simplest set of symbols that can be used to construct a turing machine. But really, couldn't you do it with just one symbol? I'm thinking along the lines of the way the natural numbers can be described by the succes...
Thu Jun 07, 2007 2:41 am UTC
Forum: Mathematics
Topic: 0!=1
Replies: 60
Views: 11761
This is really just a rewording of some posts but sometimes phraseology can make all the difference, if the factorial function describes the number of arrangements of n elements, there is only one way you can arrange zero elements. Nah, that phraseology sucks, because one might be inclined to say t...
Thu Jun 07, 2007 2:32 am UTC
Forum: Mathematics
Topic: Math Books
Replies: 42
Views: 10463
Five Golden Rules - John L Casti

This is a pretty good introduction to semi-modern theories.
Tue May 29, 2007 7:23 pm UTC
Forum: Mathematics
Topic: A matter of probability
Replies: 13
Views: 3432
How does the order of the draw come into play? 1 in 12 is obtained regardless of the order the marbles are drawn in. What would the probability be if you wanted green, green, red, but in any order?
Tue May 29, 2007 4:40 pm UTC
Forum: Mathematics
Topic: Find the error (because I sure can't)
Replies: 10
Views: 4182
Yeah, in fact I don't even think this should be categorized as a paradox. Basically you're saying "OK let's assume that element E that does NOT have property X. Now let's assume that E DOES have property X --

...

Tue May 29, 2007 3:55 pm UTC
Forum: Mathematics
Replies: 367
Views: 85499
northern_bear wrote:How many pies do you have?

None.

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V

northern_bear wrote:If you don't have any pies...
Sat May 12, 2007 1:41 am UTC
Forum: Logic Puzzles
Topic: Hello. [NUMEROLOGICAL PUZZLE, NOT SPAM - LE4dGOLEM)
Replies: 18
Views: 4373
The numbers in the 4 and 5 slot need to be swapped. The significance of the result is that it is the very same form we started with.

Edit: I think I understood the puzzle wrong
Wed May 09, 2007 4:51 pm UTC
Forum: Mathematics
Topic: 1-2+3-4... = -1/4
Replies: 22
Views: 8426
Does anyone know of a proof that 1 - 2 + 3 - 4 + . . . still converges to 1/4 (in the Cesaro sense) even if you rearrange the terms? Cesaro sums don't necessarily obey the same rules of addition that we are used to. For example, associativity: (1 - 2) + (3 - 4) + (5 - 6) + . . . = -1 + -1 + -1 + . ...
Tue May 08, 2007 10:35 pm UTC
Forum: Mathematics
Topic: 1-2+3-4... = -1/4
Replies: 22
Views: 8426
Also, I know that non-absolutely convergent series can be rearranged so as to equal any value you wish. Does this have anything to do with 1 - 2 + 3 - 4 + ...? The result you are referring to requires a series which is already known to converge, but not to absolutely converge. So that result cannot...
Tue May 08, 2007 5:55 pm UTC
Forum: Mathematics
Topic: 1-2+3-4... = -1/4
Replies: 22
Views: 8426
To show that the sum equals 1/4, they start out assuming that s = 1 - 2 + 3 - 4 + ... exists. Since it doesn't, their manipulations don't seem to be valid. I mean you could say: Let x be infinity infinity plus anything is just infinity x + 3 is infinity x + 9 is infinity x + 3 = x + 9 3 = 9 or somet...
Wed May 02, 2007 5:40 pm UTC
Forum: Mathematics
Topic: How many digits of e do you know?
Replies: 43
Views: 13924
When I worked at a call center years ago I saved my head from exploding by memorizing some e digits:

2.71828182845904523536

Although to be honest my fingers know it better than my head do. To recall it sometimes I have to imagine myself typing on the number pad.
Tue May 01, 2007 2:15 am UTC
Forum: General
Topic: Marital Arts
Replies: 207
Views: 31522
Does anyone know of a good site to visit that will help me pick a style? The only advice I've been able to find so far is "there is no best style". Makes sense, I suppose. I'd imagine certain styles work better with certain bodies. I'm about 5'5'' or so, I'd guess around 150 lbs. I want so...
Fri Apr 27, 2007 5:48 pm UTC
Forum: Logic Puzzles
Topic: A field of theorems
Replies: 12
Views: 3191
I read it as: T is the set of all theorems that can be derived from the set of axioms that define a field (so, presumably, ZF + field axioms or something?). Find a field structure on T. That is, some theorem should correspond to 0 in the field, some theorem to 1. There should be two binary operatio...
Fri Apr 27, 2007 12:17 am UTC
Forum: Logic Puzzles
Topic: Cliffjumper.
Replies: 8
Views: 3029
Also it depends on if by jumping off you mean walking off, or if you actually mean taking a big jump up into the air as you go over the cliff. Although now that I think about it, this probably doesn't make a huge difference. I doubt the differences in atmosphere resistance count for very much over s...
Thu Apr 26, 2007 11:06 pm UTC
Forum: Logic Puzzles
Topic: A field of theorems
Replies: 12
Views: 3191

### A field of theorems

This puzzle is to form a field structure over the set T, which will be defined shortly. It will be necessary to define the operators + and * as well as the identity and zero elements. T is the set of all theorems derivable from the axioms that define a field. Let us call A the set of all axioms gove...
Thu Apr 26, 2007 6:54 pm UTC
Forum: Logic Puzzles
Topic: No digit more than once
Replies: 19
Views: 5261
And when N=10, that case is impossible. You can discard the term. ;) I love it when singularities happen to line up with impossible situations! I dunno, how about 1023456789? That doesn't occur in the branch which contains the problem. :) The "impossible factorial" happens in the "no...
Thu Apr 26, 2007 5:56 pm UTC
Forum: Logic Puzzles
Topic: When is it efficient to take a bus?
Replies: 34
Views: 5823
Yakk wrote:Smart schedualers realize that people are far more upset when they arrive on time for a bus, and the bus never comes, than if the bus is a bit late.

So busses must never be early.

When my bike was out of comission I had to take the bus to school and I got so pissed for this very reason.
Wed Apr 25, 2007 10:24 pm UTC
Forum: Logic Puzzles
Topic: No digit more than once
Replies: 19
Views: 5261
Yakk wrote:And when N=10, that case is impossible. You can discard the term.

I love it when singularities happen to line up with impossible situations!

Wed Apr 25, 2007 6:45 pm UTC
Forum: Logic Puzzles
Topic: No digit more than once
Replies: 19
Views: 5261
Yakk wrote:

So, for the zero case:
9!*(N-1) / (10-N)!
Add in PaulT's "no zero" solution:
9!*[ (N-1)/(10-N)! + 1/(9-N)! ]

(9-N)! doesn't make sense when N = 10.
Wed Apr 25, 2007 5:57 pm UTC
Forum: Mathematics
Replies: 367
Views: 85499
The way I see that is each block is infinitly large and goes on forever. However you dont have any blocks so you still dont have anything. Or each box contains absolutely nothing and you may have an infinite number of them, but there is still nothing there. But 0/0 is not the total number of blocks...
Wed Apr 25, 2007 5:50 pm UTC
Forum: Logic Puzzles
Topic: When is it efficient to take a bus?
Replies: 34
Views: 5823
Pi - From the units, it looks like you calculated the minutes it would take for the bus to overtake you once the bus arrives at the first stop. x is minutes, not miles. So to finish your calculation you must take (x + 7.5 min)*(3mile/60min)*(8block/mile) = 3.5292... blocks As for the real world solu...
Wed Apr 25, 2007 5:16 pm UTC
Forum: Logic Puzzles
Topic: Sudoku Cube
Replies: 20
Views: 8522
I was asked to solve one of these by a friend. I solved it by first analyzing the rotations of the numbers and figuring out which possible orientations the faces could be in when solved. When unfolded, the cube I solved would look like this: 152 463 789 436 142 397 971 751 873 615 248 928 695 824 5...
Tue Apr 24, 2007 8:31 pm UTC
Forum: Logic Puzzles
Topic: When is it efficient to take a bus?
Replies: 34
Views: 5823
If you didn't know what time it was or the buses were unreliable, you would wait on average 15/2 min. So the time it takes to travel by bus is WAIT TIME + TRAVELING TIME. Let's say m is the number of miles to travel. The time equation in hours by bus is then: B(m) = 7.5/60 + m/20. The equation by f...
Tue Apr 24, 2007 4:56 pm UTC
Forum: Logic Puzzles
Topic: lowest-price auction variant.
Replies: 27
Views: 4544
Whether the cartel works or not depends on what happens in a tie. Case 1 (ties don't receive points): In this setup only one person at a time can collect. Let's assume we're at the point where rounds left ≤ N (players). The first person collects. Now he no longer has any way to be punished if ...
Tue Apr 24, 2007 1:25 am UTC
Forum: Logic Puzzles
Topic: lowest-price auction variant.
Replies: 27
Views: 4544
I would probably use graham's number too. But raise it to itself just to be sure.

1/(g64^g64) + n*(g64^g64)

where n = 1 if this answer is the smallest in the class and n = 0 if it is not.
Tue Apr 24, 2007 12:04 am UTC
Forum: Logic Puzzles
Topic: lowest-price auction variant.
Replies: 27
Views: 4544
Alky wrote:Versus typical math class:
First guess - 1 / busy beaver #(graham's number)
Rest of guesses - 0

Except that the rule is to write down a positive number - zero isn't allowed.