So I don't know why this went viral, but Danish newspapers started to pick it up so I guess it's time for Languish as well. It's not that difficult, but I guess if people can't tell when a dress is blue they can't do puzzles either. :P
QuoteAlbert and Bernard just became friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates.
May 15 May 16 May 19
June 17 June 18
July 14 July 16
August 14 August 15 August 17
Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively.
Albert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too.
Bernard: At first I don't know when Cheryl's birthday is, but I know now.
Albert: Then I also know when Cheryl's birthday is.
So when is Cheryl's birthday?
Also, sorry for going full Buzzfeed in the title. :blush:
The answer is 16 July by elimination.
We have 10 dates and 3 statements. Go through the statements one-by-one and cross out the ones that can't be true.
QuoteAlbert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too.
Albert only knows the month; Bernard only knows the date. For Albert to know that Bernard doesn't know, the month must not be May or June. This is because both May and June has a unique date: 18 June and 19 May. If Albert has been told May or June, a possibility will exist that Bernard will know the month simply by knowing the date: 18 or 19. For Albert to know that Bernard doesn't know, Albert must have been told either July or August. So we can safely cross out the five dates under May and June.
QuoteBernard: At first I don't know when Cheryl's birthday is, but I know now.
Ok, now we assume that Bernard has figured out the above. Bernard knows that the month must be July or August. He also knows the date. The date in his hands must be 14, 15, 16 or 17. There are five remaining possibilities. For Bernard to know the correct date for certain, the date cannot be 14, since there are two 14s in the remaining five possibilities. So Bernard must have been told 15, 16 or 17. So we can safely cross out 14 July and 14 August.
QuoteAlbert: Then I also know when Cheryl's birthday is.
So Albert has also figured out the above. He knows that the remaining possibilities are 16 July, 15 August or 17 August. Up to statement 2, Albert could be told either July or August. But from statement 3, he could not have been told August, since there are two remaining possibilities in that month. For Albert to figure out the answer for certain, he must have been told July, and there is only one remaining possibility in that month. So the solution is 16 July.
Is the answer.... 7?
July 16.
Albert can only be certain that Bernard doesn't know if Albert was told the month that did not have any unique day dates in it. So this rules out May and June.
Bernard can then know the exact birthday if it is on a unique day date of July or August - so this rules out 14 July and 14 August leaving 16 July, 15 August and 17 August.
Albert can then only know the exact date of the three only if the month he was told has only one possible day date - so 16 July.
I was quite certain Languishites would figure it out without much trouble, but why this exact question would go viral is beyond me. I mean, I love puzzles, but usually the broad public don't.
Quote from: Liep on April 15, 2015, 07:02:36 AM
I was quite certain Languishites would figure it out without much trouble, but why this exact question would go viral is beyond me. I mean, I love puzzles, but usually the broad public don't.
Yeah, simple questions like this go viral on my Facebook all the time. I guess people are dumb.
Quote from: Jaron on April 15, 2015, 06:41:20 AM
Is the answer.... 7?
Yes, if the question had been: "How many dwarves are there in the beloved Disney classic 'Snow White and The Huntsman'?"
the answer is: Cheryl isn't getting gifts or cards cause the other two were annoyed with her and her riddles... :p
Quote from: Crazy_Ivan80 on April 15, 2015, 07:17:01 AM
the answer is: Cheryl isn't getting gifts or cards cause the other two were annoyed with her and her riddles... :p
:yes:
They no longer care to know.
Maybe she likes autistic friends.
It isn't that hard. I love these kind of puzzles btw.
Cheryl's dress is blue.
Quote from: Liep on April 15, 2015, 07:02:36 AM
I was quite certain Languishites would figure it out without much trouble, but why this exact question would go viral is beyond me. I mean, I love puzzles, but usually the broad public don't.
Because it was originally and erroneously claimed to be a typical fifth grade math problem, and the working of the problem is shit. (http://www.nytimes.com/2015/04/15/science/a-math-problem-from-singapore-goes-viral-when-is-cheryls-birthday.html?_r=0) I spent three minutes trying to parse the problem. I finally gave up and reversed engineered what the problem was asking from the solution.
This thread is useless without pics of Cheryl :mad:
The more interesting question is: why do these two guys want to be friends with someone who can't even say straight what her birthday is? I imagine conversations with her are going to get old quick.
Quote from: Richard Hakluyt on April 15, 2015, 10:09:38 AM
This thread is useless without pics of Cheryl :mad:
(https://languish.org/forums/proxy.php?request=http%3A%2F%2F2.bp.blogspot.com%2F_LAuQTLgM_6o%2FRwFnEMHqRxI%2FAAAAAAAACmg%2FYOELdQnRzjw%2Fs400%2Fcheryl.jpg&hash=9357a4a4815c52d59e39aad0653eab2f0c73d69b)
If that is a picture of the Cheryl in question, I can understand why two dudes are suffering her birthdate bullshit.
I also can finally see why it went viral.
Quote from: DGuller on April 15, 2015, 10:35:24 AM
The more interesting question is: why do these two guys want to be friends with someone who can't even say straight what her birthday is? I imagine conversations with her are going to get old quick.
:o Do they know her last name?
Quote from: Martinus on April 15, 2015, 08:46:23 AM
Maybe she likes autistic friends.
Oh, come on. You do speak English. Look that word up. It doesn't meant what you think it means.