re: Are you smarter than a Singaporean 14-year-old?

The answer is....... 4

So after Albert tips off Bernard that's it's not a May or June birthday, Bernard is left with 14 July and 14 august, 16 July, 15 August, and 17 august. 14 is eliminated bc it's duplicated. But if Bernard had been given # 15 or 17 he would still know the answer and Albert wouldnt, right?

Basically, how does Albert know that he himself (Albert) now knows for sure? Bernard would still know if the day was 15 August, 17 august, or 16 July

Eta: once it's down to July and August, Bernard's certainty means it's not the 14th. Leaving us with three unique #'s: 15, 16, 17, knowing the number means knowing the answer. Let's say her bday is August 15, Bernard coukd still say "at first I did not know, but now I do." Albert has no way of knowing which of those three unique days it is

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But if Bernard had been given # 15 or 17 he would still know the answer and Albert wouldnt, right?

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Right

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Basically, how does Albert know that he himself (Albert) now knows for sure? Bernard would still know if the day was 15 August, 17 august, or 16 July

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Because Albert was given the month. Remember, first we eliminate all of May and June. That's the easiest part. But then, when Bernard states with certainty that he knows the full birthdate, that means he was given one of the remaining unique numbers, which eliminates the two 14s by default. It's only through Albert himself stating he knows the date that we are able to determine that he was told July rather than August. Take on the role of Albert yourself--and assume the bottom five dates are the only choices now. Bernard tells you that based on those five dates and the day that Cheryl told him, he knows Cheryl's full birthdate. So, you know that the day Bernard has is a day unique to the bottom 5 choices. Now, for you to be able to truthfully tell Bernard that you now know the full date, what is the only the month that Cheryl could've told you?

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Seriously the answer is not July 16. There is no way Albert coukd know the day based solely on Bernard's certainty. Am I the only one seeing this?

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Seriously, the answer is July 16, and there is no question about it. But you aren't the only one who disagrees. I have some explanations posted now (one above and on the previous page), but I guess I'm not doing the best job of explaining it. To me this like the Blue/Black dress vs. White/Gold situation. I saw Blue/Black and just could not fathom anyone seeing it any other way.

People are forgetting that we aren't trying to determine the answer for Albert, we are determining the answer because of Albert. It's only because Albert says he knows the date that we know Cheryl told him July.

The object is for the reader to come to the right answer. Thinking about the mental state of the objects in the question is irrelevant. The statements are meant to be taken as fact and assuming perfect logic between Albert and Bernard.

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Basically Albert is full of shite. He cannot know the answer based solely on Bernard's certainty.

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Albert is simply a tool to pass on the information needed to come to the right answer. Albert is not full of shite, because Albert is simply a part of the equation that has been presented.

He is no more full of shite than "2" would be in the equation "2x=6"

frick, didn't read "respectively"

If they are told the opposite info then it's June 17. Fyi

eta: July 16. easy af

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Basically Albert is full of shite. He cannot know the answer based solely on Bernard's certainty.

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No... I'm seriously trying really hard to explain this, because it's proving to be a tougher challenge than the question itself.

I'm gonna try this again from a different angle.

Let's pretend we overheard Cheryl talking to both Albert and Bernard:

Cheryl tells Albert in secret, "Albert, I was born in July."

Cheryl tells Bernard in secret, "Bernard, I was born on the 16th."

Albert then realizes, "Well, both of the possible July dates are repeated in May and August. So that means, Bernard was told either the number 14 or the number 16. For Bernard, his dates are narrowed down to either May 16 and July 16, or July 14 and August 14."



Albert's dates are narrowed down to July 14 and July 16.



Because both Bernard and Albert can only narrow it down to two possible dates, Albert can safely say, "I don't know when Cheryl's birthday is, but I know that Bernard does not know too."

Bernard now realizes that the only reason Albert would know for sure that Bernard doesn't know the date is if Albert were told a month that doesn't contain a unique number. Since Bernard was given the number 16, Bernard can eliminate May 16 because one of the May choices has a unique number (19). The only other 16 is July.



Bernard can now safely say with his shitty grammar: "At first I don't know when Cheryl's birthday, but I know now."

If Bernard can say that, then Albert knows that the number is 16, because Bernard could not have eliminated all of August based on Albert's initial assertion that Bernard doesn't know (because August has no unique numbers).

Now, try that exact scenario with any of the other dates on the list and see if it works.

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by GRTiger

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It feels good to be free. i guess I got hung up on the fact that had the date been August 15 bernard still could have been certain