## Search found 20 matches

Sat Nov 11, 2006 3:54 am UTC
Forum: Logic Puzzles
Topic: The Princess Bride variant [solution]
Replies: 26
Views: 9760
Player A can win, assuming they're allowed to screw with their own poisons. First, he drinks the weakest of his own poisons (he can assume player B will give him number 10, but just to be safe...). Then, when it's his turn to pass a poison to player B, he passes a vial of water, following which play...
Fri Nov 10, 2006 3:16 am UTC
Forum: Logic Puzzles
Topic: Pancake Problem
Replies: 56
Views: 19499
It's 2/3. Put it this way: There are 6 pancakes. Each pancake is linked to another one, A-B, C-D, and E-F. So if you get Pancake A you also get Pancake B, and so on. A-C are white and D-F are black. If you grab a pancake at random, and it happens to be black, what are the chances the other pancake y...
Sat Oct 21, 2006 2:30 am UTC
Forum: Logic Puzzles
Topic: Three princesses
Replies: 446
Views: 202811
Actually, my solution only relies on the sisters knowing their relative ages. Xandah's solution also works, as does any that effectively involves comparing an attribute that scales from the lying sister to the truth-telling sister. As far as I can think of, age and honesty are the only two such attr...
Thu Oct 12, 2006 3:20 am UTC
Forum: Logic Puzzles
Topic: Yet Another Hat Problem
Replies: 18
Views: 12036
I'm confused. If colors can be duplicated, then presumably not every color has to be used, so your hat color should be completely independent of everybody else's. How does the two-hat solution work, then (and presumably the greedy-algorithm version of it for seven hats)?
Tue Oct 10, 2006 6:50 am UTC
Forum: Logic Puzzles
Topic: Carnival of Bad Processors: solution
Replies: 15
Views: 7260
I've definitely found a pattern, but I'm still trying to figure out how to use it. Test, starting with processor 1, according to the following steps: Processor i tests Processor i+1 - If bad, skip to Processor i+2 - else, continue from Processor i+1 For every test that has a "bad" result, ...
Tue Oct 10, 2006 2:51 am UTC
Forum: Logic Puzzles
Topic: Pirate Democracy [Solution]
Replies: 27
Views: 11818
The collusion idea might work, but it's more complicated than you indicate. If 1 and 2 both vote against the first proposal, the second proposal will simply offer 1 coin to pirates 3-51. Though maybe not. The question is now whether it's logical for those pirates to accept, knowing that if they don'...
Sat Oct 07, 2006 3:04 am UTC
Forum: Logic Puzzles
Topic: Weighing Marbles
Replies: 48
Views: 43764
For extra nerdiness points, find and prove a general formula for how many marbles can be determined for an arbitrary number of weighings. I'm fairly certain I have the formula (it's a pretty straightforward extension of the discussion on this board), but I'm a little stuck on the proof.
Wed Oct 04, 2006 6:43 pm UTC
Forum: Logic Puzzles
Topic: locker problem solution
Replies: 28
Views: 21511
Wow, I think being dumb helps sometimes. This seems like an easy problem to overthink, but I got it very quickly without any real mental gymnastics. Once you figure out that each student represents a factor (student 4, for instance, will only modify lockers that are multiples of 4), it's a pretty sh...
Wed Oct 04, 2006 6:39 pm UTC
Forum: Logic Puzzles
Topic: The Locker Puzzle
Replies: 5
Views: 9620
I think I have the answer, and it seems pretty easy to arrive at if you just think about the problem in terms of factors.
Wed Oct 04, 2006 9:26 am UTC
Forum: Logic Puzzles
Topic: Sex problem
Replies: 35
Views: 15798
The question doesn't specify how you know one of the children is a boy. If you grabbed the first child and looked at its genitals, and it happened to be a boy, then the chances that the second child is a girl are 50%, since it's an independent question. If, on the other hand, all the question is say...
Tue Sep 26, 2006 2:48 am UTC
Forum: Logic Puzzles
Topic: The Cube Factory, and a Variant
Replies: 28
Views: 12182
The problem seems to be that there is an uncountably infinite set of possibilities with finite limits. As a result, wherever you put the dividing line (for the moment, we'll work with edge length, though it's the same idea for any other measurement), you'll end up with two uncountably infinite sets,...
Sun Aug 20, 2006 4:03 am UTC
Forum: Logic Puzzles
Replies: 48
Views: 22021
I can see why the jar would be empty at the end in the first case, but since that's a direct result of removing marbles from the jar on every step, I don't see where the paradox arises. Of course the jar isn't empty in the second step, you never removed the marbles you put in it. Am I missing someth...
Sat Aug 12, 2006 8:02 am UTC
Forum: Logic Puzzles
Topic: Sleeping Beauty Puzzle
Replies: 41
Views: 21554
Actually, I agree with Randy. My previous post is correct, but only if you interpret the question to mean "What is the probability the coin came up heads, disregarding the number of times you might have been asked this question?" If the princess takes into account the higher frequency with...
Sat Aug 12, 2006 7:02 am UTC
Forum: Logic Puzzles
Topic: Sleeping Beauty Puzzle
Replies: 41
Views: 21554
Sat Aug 05, 2006 2:04 am UTC
Forum: Logic Puzzles
Topic: Sum and Product Man
Replies: 27
Views: 15998
Yeah, you can eliminate any sum that is 2 more than a prime number, since that sum is then a sum of two prime numbers. That still leaves a lot of odd numbers that aren't the sums of two primes, however. This is as far as I've gotten: When the product guy indicates he knows the answer, that implies t...
Fri Aug 04, 2006 7:03 am UTC
Forum: Logic Puzzles
Topic: Sum and Product Man
Replies: 27
Views: 15998
Either I'm missing a key piece of information, or you're a bastard. I've figured out the logical implications of all the statements, weeded out all the possibilities I could ahead of time (except that I'm not sure whether all even numbers below 200 are sums of two primes), and I've still got a very ...
Fri Aug 04, 2006 1:44 am UTC
Forum: Logic Puzzles
Topic: Weighing Marbles
Replies: 48
Views: 43764
That's pretty much the answer I got (though written up far more rigorously than I bothered to). Interestingly, there were some minor differences in group composition, so I guess the answer isn't unique.
Fri Jul 28, 2006 8:12 pm UTC
Forum: Logic Puzzles
Topic: Weighing Marbles
Replies: 48
Views: 43764
Really? It seemed so hard to me. Guess I was looking at it the wrong way. Well, anybody actually having trouble finding the answer?
Fri Jul 28, 2006 6:03 am UTC
Forum: Logic Puzzles
Topic: Weighing Marbles
Replies: 48
Views: 43764

### Weighing Marbles

Here's a fun one I just heard. It took me about 6 hours to solve, and I eventually got the answer by proving that it was unsolvable, then figuring out why the proof was wrong and going from there. So if somebody solves this in half an hour, I'd appreciate it if you waited a couple hours to post the ...
Thu Jul 20, 2006 10:33 pm UTC
Forum: Logic Puzzles
Topic: Three princesses
Replies: 446
Views: 202811
Possible Solution: How about we ask daughter A "Is daughter B older than daughter C?" If daughter A is the middle daughter, it doesn't matter which of the other two we choose. If daughter A is the eldest, we marry the one she indicates is younger. If daughter A is the youngest, we want to ...