That Viral Math Problem (Cheryl's Birthday) - Numberphile
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Albert could understand that Bernard wasn't given 19 or 18 because Bernard hadn't spoken, indeed if he was given 19 or 18 he could say -I know the answer- but actually Bernard didn't do this. So also Albert couldn't give the correct answer because, even knowing that 19 and 18 aren't correct answer, he wasn't given June. Indeed if he was given June and knowing that isn't 18 or 19, he could say -the answer is 17 of June-, but actually he didn't. So, knowing that June isn't the right month, Bernard could say the answer. The only explanation is that Bernard was given 17 and the only remaining date is the 17 of August. So now also Alfred could know the answer because he understood that Bernard's number was both in June and August.
Where is my error?
Date: 2022-04-08
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Comments and reviews: 9
callum
Initially Bernard does not know, therefore it cannot be the May 19th or June 18th as they are unique dates (There is no other 18th or 19th)
Albert knows this. Therefore, it cannot be June 17 as, if he knew it were June, the 17th is the only date left after the elimination of the 18th.
Bernard knows all this and, therefore, and deduces the date only if he knows it is the 17th of August as at that point the only unique date is the 17th- the 17th of June having been eliminated. All the other dates have a pair.
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Initially Bernard does not know, therefore it cannot be the May 19th or June 18th as they are unique dates (There is no other 18th or 19th)
Albert knows this. Therefore, it cannot be June 17 as, if he knew it were June, the 17th is the only date left after the elimination of the 18th.
Bernard knows all this and, therefore, and deduces the date only if he knows it is the 17th of August as at that point the only unique date is the 17th- the 17th of June having been eliminated. All the other dates have a pair.
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Kishan
Elaborate 3rd statement - how can Albert know?
My doubt: Lets say bernard was told 17 or 15. So, now in this case also after the 1st statement by Albert, Bernard had successfully deducted his answer. (You can check no statement is violated) So if the Bernard knew the answer, how can Albert know that its not Aug 15 or 17 and its Jul 16? Based on the 3rd statement which states that Albert know the date we can deduce that it must be July as August has to options but the real question herein is how did Albert knew?
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Elaborate 3rd statement - how can Albert know?
My doubt: Lets say bernard was told 17 or 15. So, now in this case also after the 1st statement by Albert, Bernard had successfully deducted his answer. (You can check no statement is violated) So if the Bernard knew the answer, how can Albert know that its not Aug 15 or 17 and its Jul 16? Based on the 3rd statement which states that Albert know the date we can deduce that it must be July as August has to options but the real question herein is how did Albert knew?
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FortNikitaBullion
#1: 1993 Mathcounts National Team Round #4: The teacher whispers positive integer A to Anna, B to Brett, and C to Chris. The students don't know one another's numbers but they do know that the sum of their numbers is 14. Anna says: -I know that Brett and Chris have different numbers. - Then Brett says: -I already knew that all three of our numbers were different. - Finally, Chris announces: -Now I know all three of our numbers. - What is the product ABC?
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#1: 1993 Mathcounts National Team Round #4: The teacher whispers positive integer A to Anna, B to Brett, and C to Chris. The students don't know one another's numbers but they do know that the sum of their numbers is 14. Anna says: -I know that Brett and Chris have different numbers. - Then Brett says: -I already knew that all three of our numbers were different. - Finally, Chris announces: -Now I know all three of our numbers. - What is the product ABC?
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Stu
I took FAR too long to understand why May got discarded along with June.
Guess I'm one of those people who focuses on the language rather than the maths lol.
Wasn't until the second video that I twigged -oh they don't actually confer privately to see if the other knows the answer from their one clue- - now Albert confidently claiming -Bernard doesn't know- makes it obvious that he doesn't have May as his clue.
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I took FAR too long to understand why May got discarded along with June.
Guess I'm one of those people who focuses on the language rather than the maths lol.
Wasn't until the second video that I twigged -oh they don't actually confer privately to see if the other knows the answer from their one clue- - now Albert confidently claiming -Bernard doesn't know- makes it obvious that he doesn't have May as his clue.
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MB
I couldn't understand how Albert could say I know when Bernard said he knows. Coz out of those three options that were left with Bernard, the real date could have been any of those three, including the month with two dates, so how could Albert deduce that what Bernard knows is the date of the month with only one date.
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I couldn't understand how Albert could say I know when Bernard said he knows. Coz out of those three options that were left with Bernard, the real date could have been any of those three, including the month with two dates, so how could Albert deduce that what Bernard knows is the date of the month with only one date.
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Wobblyorbee
My last digit is 3 more than my first digit.
I am less than 285.
My first digit is smaller than 7.
The sum of my digits is 15.
What number am I?
Please numberphile, I made a question for you to answer. I want to see that you get this hard or not. Please reply me: -)
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My last digit is 3 more than my first digit.
I am less than 285.
My first digit is smaller than 7.
The sum of my digits is 15.
What number am I?
Please numberphile, I made a question for you to answer. I want to see that you get this hard or not. Please reply me: -)
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Shane
Hopefully someone reads this. When Bernard says that he knows, why could it have not been August 15th or 17th? Yes, there still was two options in August, but each date is unique, so if he had 15 or 17, then he knows it would have been August. This has been doing my head in!
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Hopefully someone reads this. When Bernard says that he knows, why could it have not been August 15th or 17th? Yes, there still was two options in August, but each date is unique, so if he had 15 or 17, then he knows it would have been August. This has been doing my head in!
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Nigel
These were always my least favorite professor Layton puzzles tbh, because of the ambiguous language. I'd always prefer if the wording didn't beat around the bush with wording, since half the puzzle becomes inferring what Bernard meant, rather than applying logic.
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These were always my least favorite professor Layton puzzles tbh, because of the ambiguous language. I'd always prefer if the wording didn't beat around the bush with wording, since half the puzzle becomes inferring what Bernard meant, rather than applying logic.
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The
When I tried solving it, guessing off of Albert's inclusion of the word -too- I assumed it was the second month June, then with Bernard's inclusion of -first- I assumed he was referring to the first date of that moth making it June 17, easy and far more realistic
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When I tried solving it, guessing off of Albert's inclusion of the word -too- I assumed it was the second month June, then with Bernard's inclusion of -first- I assumed he was referring to the first date of that moth making it June 17, easy and far more realistic
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