As was foretold, we've added advertisements to the forums! If you have questions, or if you encounter any bugs, please visit this thread: https://forums.penny-arcade.com/discussion/240191/forum-advertisement-faq-and-reports-thread/
Options
Come [Puzzle] With Me
AngelHedgie
Registered User regular
Registered User regular
So, the Internet's brain has once again been broken, this time by a puzzle out of a math olympiad:
It's not all that difficult, as the form goes, but it's nice to see the attention of the internet captured by logic, as opposed to what normally catches its eye. So, in the spirit of this, I want to open the floor for everyone to put forth their love of puzzles, riddles, and other conundrums of logic, for us to share and beat our heads in with.
Well, with one caveat. There is one logic puzzle that is not welcome here, because it pretty much has derailed any other prior puzzle thread we've had. So, as a rule, discussion of the Monty Hall Problem is verboten. Yes, we know it seems unintuitive. But it's been discussed to death before, so let's let it rest in peace.
Albert and Bernard just met Cheryl. “When’s your birthday?” Albert asked Cheryl.
Cheryl thought a second and said, “I’m not going to tell you, but I’ll give you some clues.” She wrote down a list of 10 dates:
May 15 — May 16 — May 19
June 17 — June 18
July 14 — July 16
August 14 — August 15 — August 17
“My birthday is one of these,” she said.
Then Cheryl whispered in Albert’s ear the month — and only the month — of her birthday. To Bernard, she whispered the day, and only the day.
“Can you figure it out now?” she asked Albert.
Albert: I don’t know when your birthday is, but I know Bernard doesn’t know, either.
Bernard: I didn’t know originally, but now I do.
Albert: Well, now I know, too!
When is Cheryl’s birthday?
It's not all that difficult, as the form goes, but it's nice to see the attention of the internet captured by logic, as opposed to what normally catches its eye. So, in the spirit of this, I want to open the floor for everyone to put forth their love of puzzles, riddles, and other conundrums of logic, for us to share and beat our heads in with.
Well, with one caveat. There is one logic puzzle that is not welcome here, because it pretty much has derailed any other prior puzzle thread we've had. So, as a rule, discussion of the Monty Hall Problem is verboten. Yes, we know it seems unintuitive. But it's been discussed to death before, so let's let it rest in peace.
XBL: Nox Aeternum / PSN: NoxAeternum / NN:NoxAeternum / Steam: noxaeternum
0
Posts
It goes backward forward in daylight, left and right then out of sight.
It's hot and cold without a doubt, like sun and moon twirling about.
It's north south east and west, black white and all the rest.
Good luck in solving this little chime, you'll be at it 'til the end of time."
what is it, and why..?
I posted a similar(ish) puzzle in a thread here years ago, which I always thought was called the product-sum puzzle or something similar, but which Wikipedia informs me is inaccurately called "The Impossible Puzzle". The statement is as follows:
There are many variations with more statements (and hence different answers, naturally). Also I'm pretty sure Wikipedia's assertion "with sum less than 100" can be replaced by "with each less than 100" and you still get the same solution.
Note the solution (with a long-winded explanation) is available on the Wikipedia article. So, don't look there if you're interested in solving it yourself.
Also note this can be done with pencil and paper (that is how I solved it when I first encountered it), but you can save yourself quite a bit of writing with very basic programming.
EDIT: I'll also say that while I can't guarantee a satisfying answer, I can guarantee that the solutions for this problem and the OP's problem are certainly not arbitrary
EDIT2: Oh dear, I'm gradually realizing you weren't referring to the OP puzzle.
Oh man I remember this one. Pages and pages of guesses and then the answer was something utterly arbitrary and my memory is hazy but I think we hunted down and killed whoever posted it in a blind rage.
Choose Your Own Chat 1 Choose Your Own Chat 2 Choose Your Own Chat 3
Right on both counts.
It is/was literally the worst.
Salt n'Peppa for obvious reasons
Edit: the alternate form of that reason was pretty good to
Sometimes I'm false and sometimes I'm true,
I might have a giraffe, or a George Foreman Grill,
And you'll never solve me, because I'm a terrible riddle
For the record the guy said that the riddle was "something specific and not general like love of god" and then that is exactly what the fucking answer was.
Salt'n'Peppa will always be the true answer to the bullshit word puzzle.
fffffffffffffffffff
Choose Your Own Chat 1 Choose Your Own Chat 2 Choose Your Own Chat 3
Some people find them annoyingly arbitrary, but they've been lifesavers during long car trips or to keep kids' attention.
My favourites (there's no point trying to solve them here as the thread would be dominated by questions just about these riddles, so I'll just put the answers - feel free to try them out with friends):
A surgeon approaches a tramp in New York City, and offers him $5,000 for his left arm. The tramp agrees, and the surgeon removes the arm, pays the tramp, and they go their separate ways. The surgeon then packs the arm in ice and posts it to Las Vegas, where six men are waiting for it. They open the package, see what's inside, then drive out into the desert and bury it. They then go their separate ways. Why?
A man is passing a clifftop restaurant that boasts albatross pie on the menu. He enters and orders it. When the pie arrives, he takes one bite, pays the bill, then goes outside and throws himself off the cliff to his death. Why?
It's meant for kids. That the Internet was enthralled by it is interesting, because if you've got any experience with logic or math, it should be solvable it seconds. Provided you don't get caught up quibbling over wording.
- There are five houses.
- The Englishman lives in the red house.
- The Spaniard owns the dog.
- Coffee is drunk in the green house.
- The Ukrainian drinks tea.
- The green house is immediately to the right of the ivory house.
- The Old Gold smoker owns snails.
- Kools are smoked in the yellow house.
- Milk is drunk in the middle house.
- The Norwegian lives in the first house.
- The man who smokes Chesterfields lives in the house next to the man with the fox.
- Kools are smoked in a house next to the house where the horse is kept.
- The Lucky Strike smoker drinks orange juice.
- The Japanese smokes Parliaments.
- The Norwegian lives next to the blue house.
Now, who drinks water? Who owns the zebra?In the interest of clarity, it must be added that each of the five houses is painted a different color, and their inhabitants are of different national extractions, own different pets, drink different beverages and smoke different brands of American cigarets [sic]. One other thing: in statement 6, right means your right.
Here are a pair that my dad got from a coworker:
A guy has two bottles of seemingly identical pills, each with the same number currently in them. He has to take exactly one pill from each every day, no more and no less, otherwise he dies. One day, he drops the bottles and three pills fall out (edit: two from one bottle and one from the other). What does he do?
also he lives in a hellish dystopia and can't afford to just toss the pills or something, i dunno
A gal wants to paint the area between two concentric circles. What is the smallest number of measurements she needs to make to find the area of what she'll be painting?
The derivation is left as an exercise for the reader.
edit: Also, in the birthday problem, it is kind of super important that A and B both know that C told one of them the month and the other the date. It's not made explicit in that version.
edit edit: Apparently it's not explicit in the original version either, but the revised one makes it even LESS clear. So good job NYTimes or whomever.
Here's one:
I don't think the two puzzles are wholly similar. The puzzle you are giving is just a logic grid puzzle, which only requires information you know. The puzzle in the OP specifically requires you to consider what other people know and what they know the other person knows. That is, at the very least, a lot harder for people to understand than solving a large grid based solely on what they know.
Salt'n'Pepa is one of my proudest forum moments. It am delighted that it is remembered so fondly.
the "no true scotch man" fallacy.
I had a game called Mindtrap as a kid that had a lot of riddles like this
they always did, and still do, give me the fucking chills more than almost anything I've ever read. I'm not sure why. But I also like them and will read straight through to the answers without even trying too hard because I find them super satisfying.
does it also explain the interaction between a hypothetical airplane and treadmill?
Here are some heroes and villains from the Marvel Universe. Can you identify the character, and place all of them in the correct order? Explain why you think the order is correct in a spoiler.
Hint: I took the pictures directly from the Marvel website character listings, if you are having problems identifying the characters.
EDIT: Put the pictures in a spoiler. I'm anticipating quote trees, and it might get a little messy if these pictures are quoted a lot.
Possible ways of arranging giving it 10 seconds of thought:
Order of appearance.
Power level.
Some sort of creation myth or cycle that has some author-specific permutation of Phoenix -> Sun(fire) -> Moon (knight) -> Lightning (Thor) -> Klaw (sound) -> Cyclops (Concussive) -> Mandarin (Man)
EDIT: If it has anything to do with the latter one, I'm really not interested in solving it further because that either involves a made up cycle or searching through a creation myth that contains all of those, and none of the ones I can think of (Judeo-Christian, Islamic, Babylonian, Shinto, Voodoo) include all the pieces.
I feel like I'm missing something, but that's where I'm at. Close? Far?
Answer:
If it was, then the date could be the 18th or the 19th, in which case it would be possible for Bernard to know because each of those dates only shows up once in the list
Eliminating those two months erases the ambiguity of the date Bernard was given. So the date must be one that was in either July or August, but NOT both, and which was in either May or June or both
The only date that fits the criteria is August 17.
Therefore her birthday is August 17.
Right?
http://www.audioentropy.com/
B knows it now, so it can't be the 14th - July 16, Aug 15/17 left.
However because A also knows it after that, and A wouldn't be able to if it was august, only possibility is July 16
The only way A can know that B wasn't told 18 or 19 (which would let B know the month as well, since both those only appear once) is if A was told July or August.
B now knows that A was told either July or August.
B now knows the date and month, and says so. This means that B wasn't told 14, otherwise he couldn't be sure of the month. He was either told 15, 16, or 17, and can match any of those to the appropriate month.
Now A also knows the date and month. The only way A can know the date is if there is only one option available to B given the date. If the birthday was August 15th or 17th, A wouldn't be able to know which one. He would know what he was told (August) and that B was told either 15 or 17, but not which.
Therefore, A had to have been told July, and B had to have been told 16.
Herself: She's no logician and the table of assholes gave her a headache so she poured herself a cup of coffee and wept at the futility of her job and life in general.
I've been thinking on this all day and I had similar thinking
In his arguments for what's wrong with the logical argument that the treasure is in the red box, he says this:
The problem is that if the treasure is in the green box, the label isn't just inconsistent, but out and out paradoxical. If the treasure is in the green box, then the label on it (the treasure is in this box) is true. Which means that there's no way to get a logical value on the label on the red box that doesn't go and turn around (If we hold that this means that BOTH labels are true, then the statement of the red label is then false, which in turn means that only ONE label is true, which means that the red label is actually true, which means that BOTH labels are true...you get the point.) Since the rules of the game mean we cannot have a paradox, we can safely eliminate the green box. Only by placing the treasure in the red box do we enter into a fully logically consistent state.
The same sort of argument is used as the proof that the halting problem cannot be solved.
Taken another way, the first step of induction isn't to look at a single neighbor and predict what that neighbor is thinking looking down a chain of neighbors. The first step is to look at what all of the neighbors are thinking, and then what all of the neighbors are thinking all of their other neighbors are thinking, and then what all of the neighbors are thinking all of their other neighbors are thinking all of their other neighbors are thinking, and so on. You can't act like an actor deep in the chain is ignorant when evaluating the chain in a different order would indicate that it's much better informed.
Edit: Eh, adding link.
It doesn't matter what is written on the box because which box the treasure is in is not tied to the labels. Which is why there isn't enough info.
And of course Monty hall question has Monty hall answer. Though I feel this one is easier than the original.