This is one of the most clever logic puzzles I've seen. Congrats if you solve it without cheating

Here's the better version that is very original

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>> Since A knows B does not know it can't be in a month that includes a unique date, ie. May or June
how the hell do you arrive at that?

Seen this a couple of times.

It's 16th of July and not that hard to figure out.

got it too

pic is my doodles, might help

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if A was told it was in May then he can't exclude May 19 as a possible date and if May 19 is correct then B knows the date automatically since no other month has the number 19
Ie. since A knows B can't know then the month must only have dates that appear in at least one other month

you should be able to solve this

hint: keep in mind that cost is not the same as price

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what
$2 rite?

the answer is cheryl is a fucking whore and about to be spit roasted by two chads and needs to stop with the mind games

Seems right to me.

>Month must be ambiguous because Albert doesn't know. All months are ambiguous, red herring
>Day must be unambiguous because Bernard knows
>The only Day which is not ambiguous is 19, so it is May 19th

did I win

but how does albert know when the birthday is if he's left with 16 july, 15 august and 17 august?

Try thinking about it. I'm sure you'll figure it out by yourself.

He knows the month
that's how we know it's July because if it was August Albert couldn't figure it out between 15 and 17

Hah, those idiots selling it are losing out on 0.33 dollars per sale.

yep, got it, thanks

that is the dumbest answer so far

you're the dumbest answer so far

>a knows b doesn't know, so it's not a single-occurence day - rule out may 19 and june 18
>given only month, this means it cannot be may or june
>b now knows d and that it is july or august
>if d=14 m is unknown to b so d=/=14
>if m was august, a would not know day but if a and b both know it should be july 16?

I accept being retarded for the simple fact of not taking the time to think this through seeing how it might have been hard. Not like I had anything going for me anyway.

How the fuck could it ever be 19, if she said the number 19 to either of them then that person would know the answer immediately which is not the case, they need the combined knowledge of the certainty that it is not a date that one person can figure out by themselves

3?

1/2(x) = x/2x ?

im a brainlet pls help

2
1+x/2 = x -> 1 = x/2 -> x = 2

Since Cost (C) != Price (P)
C = 1 + P/2
Two variables one equation. You would need more info to solve it.

i'm going insane, if bernard knows the day why the fact that albert knows that beranrd doesn't know is at all relevant to him? doesn't he already know the number and that it isn't a unique one?
i think there's some double meaning on the phrase 'he knows he doesn't know'.

Why does the fact that B doesn't know exclude May and June? Doesn't it just exclude May 19th and June 18th, but not the other dates in those months?

There's no double meaning. The logic is sound and straight forward. Keep thinking about it. Let it drive you crazy. When you have your eureka moment you'll be wowed.

Thanks, i really struggled there. Now i know i'm fucking retarded.

its frickin 1.5
1 for the ticket and + 0.5 for the added half.

How do you figure out the price?

you can choose to focus on just the fact that Bernard did not know until Albert told him he didn't know either
the two are equivelant

A knows the month, not the dates

WHAT PEOPLE ARE NOT GETTING IS THAT BOTH BERNARD AND THE OTHER FAGGOT GET TO SEE THE LIST OF ALL THE DATES LISTED
THEY BOTH KNOW 19 AND 18 ARE UNIQUE, THEY CAN REVIEW THE LIST

This is retarded and there isn't enough information, kill yourself.

you're the retard here
the correct answer with the full walkthrough has already been posted twice itt

Hey dude, i got you, also had the same problem. B doesn't know the month but knows the day. So if B knows the day, and B was told that it was 18 or 19 then he would automatically know the month too just by looking at the list.

A knows B doesn't know, which means it's not May 19th or June 18th, but why can't it for example be May 15th, May 16th, or June 17th?

I thought the same thing until i've read the explanation. We're just dumb as fuck.

...but he doesn't know (not in the beginning)

because A knows the month and only the month
if it was any date in May or June A couldn't exclude the unique dates and couldn't therefore be sure B didn't know

i got it, but know i'm going insane. how does barnard understand the birthday on the fact that albert knows that barnard doesn't know if barnard already knows he doesn't know? anyone could've said that barnard didn't know the birthday, because everyone knew he only had the day. am i a brainlet?

Because you're too dumb to get it.

>am i a brainlet?
that's how it's looking m8

please explain, my brain is hurting

B was told the day at the beginning so you can rule out june 18 and may 19 because otherwise B would have figured out that it was june 18 or may 19.

How does b not know then suddenly know? He knew as soon as he recived the date irespective of A?

i could've said that barnard dindn't know, it woulldn't add any information and barnard already knew it because if it was an unique number he wouldn't need the information that albert knows he doesn't know. am i explaining myself?

just ask Bernard?

before hearing Albert Bernard only knows the date is 16 meaning it could be May 16 or July 16
when Albert says he knows for certainty B does not know B realizes May is not an option because then Albert couldn't exclude May 19 which has a unique number
This means Bernard suddenly knows May 16 is not an option, leaving only July 16 from Bernard's pov meaning he now knows the date and month

This actually really helped me, thanks

crash the train with no survivors

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July 16
Thought it was June 17 for a minute but redid it

Yeah but if Bernard is left with July and August as only options, why couldn't he deduce that 15 or 17 belong in august, since those are unique to that month? In that case Albert still wouldn't know for sure it's July 16

you must be american

wasabi

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$1.50 duh origamoee

This one is incredibly easy, the only tricky part is the way it's worded.

>Cheryl then tells Albert and bernard separately the month and day of her birthday respectively

The respectively bit indicates that albert was told only the month and bernard was told only the day but the way it's written threw me off because I hardly ever see respectively used correctly and I skipped over it due to tabbing back and forth between this thread and what game i was playing. Could have just used

Bernard knows the number so it can only be July 16 from his perspective
Albert knows the month so he doesn't have to deduce anything at that stage

Certainty is the key here
A knows B does not know with full certainty, so that instantly rules out June and May
It can't be 14 as that would make both July and August possible
And it can't be August because then both 15 and 17 would be possible
So it's july 16

yeah, that's true. I overlooked the fact that albert knows the month already

I always assume these are a paradoxical brain teaser meant to make your brain run in circles and thus have never put much effort into solving them.

Why does it rule out may? What if she said the month was may and day the 16th? They'd both be stuck with either may 16 or july 16. How can they deduce it?

alright, not that hard once you write it down.
1 + 0.5*P = P (or 1 P to make it clear)
=> 1 = 0.5*P => P = 2
so the thing costs two dollars

if it was May Albert couldn't have known Bernard didn't know, that's the first clue to eliminating May and June as options

Literally the exact same problem put on a trolley. The answer is C3

>before hearing Albert Bernard only knows the date is 16 meaning it could be May 16 or July 16
but we don't actually know the date is 16, this is something you know based on a logic that i was criticizing.
now, lets go slow
>albert knows the month
>b the day
>a says he doesn't know and that b doesn't know either
>for b to don't know it needs for the date to not be an unique number
>but b already knew it wasn't an unique number
>so why the information given by a is at all meaningful to him?
and if you gave me the answer in the privious post i honestly didn't understand, maybe the fact that english isn't my langauge is a factor here, i dont know. please, someone help a brainlet out.

He would know bernard didn't know because there are three options for may, eliminating 19th because its unique, 15 and 16 left since bernard can't find out because there are 2x15ths and 2x16ths.

i'm going to bed soon and i wont be able to sleep if someone doesn't explain it to me

literally that's the only right solution

>>so why the information given by a is at all meaningful to him?
because knowing that A knows a unique date is impossible wipes out the entire months of June and May, not just the specific dates

Knowing b can't know only eliminates june as an option not may

June 18

OP, I did it half by gut feeling. Tell me if it's correct and I'll post the thought process.

It would have to be either june 18th or may 19th. I honestly dont know how to deduce it any further though.

Why does it wipe May out? May has three dates

Guys don't forget B knowing right away is also a clue, because that rules out all uncertainties

if Albert hears May then Albert can't eliminate May 19 as the date
if May 19 is the date then Bernard knows just from the number
so if May is the month Albert can't know Bernard doesn't know
but Albert does know Bernard doesn't know so clearly May is not it

completely wrong

also completely wrong
think about it, if it's June 18 or May 19 how does Albert know Bernard doesn't know?

If a knows its may he can eliminate 19 by knowing b doesn't know the date because 19 is unique to may, thus, eliminating 18 of june and then the entire month. Now he knows it can't be 17th either because b would come to same conclusion. Still leaving may 15 and 16 and all other dates in play

im a bit stumped on the second part of the puzzle
why does excluding june 18th and may 19th also exclude may 15, may 16, and june 17?

>If a knows its may he can eliminate 19 by knowing b doesn't know
let me stop you right there
A doesn't know B doesn't know automatically - he deduces it from the fact that July is the month and July contains no unique dates

I still don't get it. Who said A knows it's in May? What if he just has no idea? This doesn't make sense to me.

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It's August 17.

You have to assume both Albert and Bernard are perfect logicians. Albert knows the month and Bernard knows the date.

It cannot be May 19 or June 18 since these have a unique date. If it was one of these dates Bernard would know instantly.

Albert knows this because he knows Bernard hasn't figured it out.

Bernard figures out it isn't in June. Because if it was in June, then Albert would have figured it out immediately (since Albert knows June 18 is now invalid).

Bernard then says he figured it out. Since excluding June 17 would make August 17
the only date now with a unique number - this must be the number Cheryl told him. Bernard would not be able to come to this conclusion otherwise.

Assuming Albert is a perfect logician like us - he figured the same out the same way we did.

Source: I'm an INTP

Explain how you know this?

>because knowing that A knows a unique date is impossible
This is correct, but you're not explaining it clearly enough for him. The information is significant because B learning that A understands that it's not unique means that it MUST BE ONE OF THE MONTHS that DO NOT have unique numbers in them: it must be July or August.

B = Bernard
A= Albert
B knows the day
A knows the month
B is informed that he could not possibly know the date of the birthday by A, the person who knows the correct month, implying that the day that B should know could not be unique, since A told him that he knows B shouldn't know from just his information alone. B now knows the month, too, since he was split between 2 months, one having a unique number and one NOT having a unique number. B knows the birthday and tells A that he knows the birthday.
BECAUSE B was able to figure it out, and A knows the real month, A knows which day it must be now, as well. Because A was able to figure out the correct birthday, it must not be a month that has two possible answers that B could've narrowed down to, eliminating August as an option, since both August 15th and August 17th fit the criteria of being days that are non-unique and their matching day-pairs belonging to a month containing a unique numbered day, leaving July 16th, which is a month and day that fits the criteria of being a non-unique day with an identical day number in a month with a unique day that could be eliminated AND has no other possible solutions within the month, allowing Albert(A), who knows the correct month, to solve the birthday

This is what i think the Answer is

>What if he just has no idea?
A always knows the month, that's how the problem is given

from the statement of the problem
it doesn't say that A is told B doesn't know and it's a logic puzzle so we work with the information we're given

Because A only knows the month and that B can't know, if it were may or june he wouldn't know for sure that B can't know as it might be on 18 or 19. So that means A knows it's not on may or june.

oh I missed a part in the question I'm retraded

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a said that he knew that barnard didn't knew based on axiom(a doesn't know why b doesn't know either) and since the day that b knows to be true is 16 he still doesn't have any information to say that it isn't may 16. why b understand it isn't may if he knows the day is 16? it doesn't make sense

this is wrong
correct answer is

This is how far i've gotten, can anyone conclude anything based on this?

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ah. makes sense. i get it now. cheers