When is Cheryl's Birthday?
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Cheryl has a birthday, and she doesn't want to share it right away. (Otherwise, we have no challenge to solve.) So she gives her friends Albert and Bernard a list of 10 possible birthday dates: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15 or August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. We then have a conversation which progresses as below - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too. Bernard: At first I don't [sic] know when Cheryl's birthday is, but I know now. Albert: Then I also know when Cheryl's birthday is. So, it is possible to deduce Cheryl's birthday? I'm surprised this was not posted here before. Its become fairly popular recently. Of course, try to solve it without searching on the internet! Not much fun otherwise. :D
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Cheryl has a birthday, and she doesn't want to share it right away. (Otherwise, we have no challenge to solve.) So she gives her friends Albert and Bernard a list of 10 possible birthday dates: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15 or August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. We then have a conversation which progresses as below - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too. Bernard: At first I don't [sic] know when Cheryl's birthday is, but I know now. Albert: Then I also know when Cheryl's birthday is. So, it is possible to deduce Cheryl's birthday? I'm surprised this was not posted here before. Its become fairly popular recently. Of course, try to solve it without searching on the internet! Not much fun otherwise. :D
Mobile Apps - Sound Meter | Color Analyzer | SMBC | Football Doodles
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Cheryl has a birthday, and she doesn't want to share it right away. (Otherwise, we have no challenge to solve.) So she gives her friends Albert and Bernard a list of 10 possible birthday dates: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15 or August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. We then have a conversation which progresses as below - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too. Bernard: At first I don't [sic] know when Cheryl's birthday is, but I know now. Albert: Then I also know when Cheryl's birthday is. So, it is possible to deduce Cheryl's birthday? I'm surprised this was not posted here before. Its become fairly popular recently. Of course, try to solve it without searching on the internet! Not much fun otherwise. :D
Mobile Apps - Sound Meter | Color Analyzer | SMBC | Football Doodles
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Here's another question: Cheryl is 21 years older than her son. 6 years from now, she will be 5 times as old as him. Question: where is the son's father? ;)
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Here's another question: Cheryl is 21 years older than her son. 6 years from now, she will be 5 times as old as him. Question: where is the son's father? ;)
In jail, I hope...
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Cheryl has a birthday, and she doesn't want to share it right away. (Otherwise, we have no challenge to solve.) So she gives her friends Albert and Bernard a list of 10 possible birthday dates: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15 or August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. We then have a conversation which progresses as below - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too. Bernard: At first I don't [sic] know when Cheryl's birthday is, but I know now. Albert: Then I also know when Cheryl's birthday is. So, it is possible to deduce Cheryl's birthday? I'm surprised this was not posted here before. Its become fairly popular recently. Of course, try to solve it without searching on the internet! Not much fun otherwise. :D
Mobile Apps - Sound Meter | Color Analyzer | SMBC | Football Doodles
I never got around to getting into the big deal about this - but as now it hit CP, I took a look. Not particularly difficulty (why was there such a (media/internet) fuss if this was the problem?) and yet a pleasant exercise as I rarely have time for these these days. Presuming I got it right with July 16th, that is . . .
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"As far as we know, our computer has never had an undetected error." - Weisert
"If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
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In jail, I hope...
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Here's another question: Cheryl is 21 years older than her son. 6 years from now, she will be 5 times as old as him. Question: where is the son's father? ;)
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Someone else told me the same answer once. He made a mistake in his calculation. I guess you did too.
Nah - I just don't like the guy... :laugh:
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Here's another question: Cheryl is 21 years older than her son. 6 years from now, she will be 5 times as old as him. Question: where is the son's father? ;)
The future child's age is at the time -¾ of a year (negative three quarters). That's nine months yet-to-be-born. Assuming it is a normal pregnancy, and given the fact that you have a joke icon in your post (and that I might have heard that joke before), then most probably the answer is:
He is on top of her! FWIW: He could also be under, at a side or at a plethora of other angles. Sexual liberation has screwed math! Anyway, long-stretch assumptions, approximate calculations and probabilities are more in the realm of physics (although too many aspects of software development also come to mind).Anything that could possibly go wrong in some moment, will definitely go wrong in the worst possible moment...
In the worst way that could be possible!–Finagle's corollary to Murphy's Law (paraphrased).
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Cheryl has a birthday, and she doesn't want to share it right away. (Otherwise, we have no challenge to solve.) So she gives her friends Albert and Bernard a list of 10 possible birthday dates: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15 or August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. We then have a conversation which progresses as below - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too. Bernard: At first I don't [sic] know when Cheryl's birthday is, but I know now. Albert: Then I also know when Cheryl's birthday is. So, it is possible to deduce Cheryl's birthday? I'm surprised this was not posted here before. Its become fairly popular recently. Of course, try to solve it without searching on the internet! Not much fun otherwise. :D
Mobile Apps - Sound Meter | Color Analyzer | SMBC | Football Doodles
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New version: WinHeist Version 2.1.1 new web site. I know the voices in my head are not real but damn they come up with some good ideas!
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42
New version: WinHeist Version 2.1.1 new web site. I know the voices in my head are not real but damn they come up with some good ideas!
Jokers are not allowed, not even this one.
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Cheryl has a birthday, and she doesn't want to share it right away. (Otherwise, we have no challenge to solve.) So she gives her friends Albert and Bernard a list of 10 possible birthday dates: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15 or August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. We then have a conversation which progresses as below - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too. Bernard: At first I don't [sic] know when Cheryl's birthday is, but I know now. Albert: Then I also know when Cheryl's birthday is. So, it is possible to deduce Cheryl's birthday? I'm surprised this was not posted here before. Its become fairly popular recently. Of course, try to solve it without searching on the internet! Not much fun otherwise. :D
Mobile Apps - Sound Meter | Color Analyzer | SMBC | Football Doodles
Now this is the Cheryl on the cake.
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Cheryl has a birthday, and she doesn't want to share it right away. (Otherwise, we have no challenge to solve.) So she gives her friends Albert and Bernard a list of 10 possible birthday dates: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15 or August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. We then have a conversation which progresses as below - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too. Bernard: At first I don't [sic] know when Cheryl's birthday is, but I know now. Albert: Then I also know when Cheryl's birthday is. So, it is possible to deduce Cheryl's birthday? I'm surprised this was not posted here before. Its become fairly popular recently. Of course, try to solve it without searching on the internet! Not much fun otherwise. :D
Mobile Apps - Sound Meter | Color Analyzer | SMBC | Football Doodles
Helping your kid with their Common core again?
If it's not broken, fix it until it is
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I never got around to getting into the big deal about this - but as now it hit CP, I took a look. Not particularly difficulty (why was there such a (media/internet) fuss if this was the problem?) and yet a pleasant exercise as I rarely have time for these these days. Presuming I got it right with July 16th, that is . . .
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"As far as we know, our computer has never had an undetected error." - Weisert
"If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
The big fuss was because it was set in a SAT style test for children 5 years younger than intended and all the little dears went home and cried to their over-protective parents who had failed to teach them that it was OK to admit that there are some things you can't do when you're 10 that you will be able to do when you're 15 and responded by attacking the education authorities rather than deal with their own lack of parenting skills.
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The big fuss was because it was set in a SAT style test for children 5 years younger than intended and all the little dears went home and cried to their over-protective parents who had failed to teach them that it was OK to admit that there are some things you can't do when you're 10 that you will be able to do when you're 15 and responded by attacking the education authorities rather than deal with their own lack of parenting skills.
Well - in this case I understand the fuss - but on a different level. To put that type of question on the test clearly calls into question the designer of the test. A test should be difficult enough to allow adequate differentiation amongst those taking it - so a test where no one gets 100% is ideal. On the other hand - putting material into a test is an implicit indication that you should know how to answer it. The injection of an unnerving experience into the test (unless it was for some reason testing this unnerving phenomenon) is incompetent if not outright sadistic. Actually - you bring back a memory of my own in such a matter (and I always did very well on standardized exams): a question on a state-wide exam asked for what cause a certain person was famous. It turns out they were a furniture designer. That question was absolutely without any merit (and possible added so certain person's offspring can pick up an extra 4-pts). It lay completely out of place not only based upon standard curriculum, but beyond the knowledge and interests of all but a select few. But, back to the subject: Perhaps the outrage of the parents is not incorrect, but merely misplaced - their should really be an inquiry into what motivated inclusion a question of such a nature. My view of psychologists and sociologists is that they'd not have any qualms about screwing with large numbers of children just to see how it affects them.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"As far as we know, our computer has never had an undetected error." - Weisert
"If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
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Well - in this case I understand the fuss - but on a different level. To put that type of question on the test clearly calls into question the designer of the test. A test should be difficult enough to allow adequate differentiation amongst those taking it - so a test where no one gets 100% is ideal. On the other hand - putting material into a test is an implicit indication that you should know how to answer it. The injection of an unnerving experience into the test (unless it was for some reason testing this unnerving phenomenon) is incompetent if not outright sadistic. Actually - you bring back a memory of my own in such a matter (and I always did very well on standardized exams): a question on a state-wide exam asked for what cause a certain person was famous. It turns out they were a furniture designer. That question was absolutely without any merit (and possible added so certain person's offspring can pick up an extra 4-pts). It lay completely out of place not only based upon standard curriculum, but beyond the knowledge and interests of all but a select few. But, back to the subject: Perhaps the outrage of the parents is not incorrect, but merely misplaced - their should really be an inquiry into what motivated inclusion a question of such a nature. My view of psychologists and sociologists is that they'd not have any qualms about screwing with large numbers of children just to see how it affects them.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"As far as we know, our computer has never had an undetected error." - Weisert
"If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
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Cheryl has a birthday, and she doesn't want to share it right away. (Otherwise, we have no challenge to solve.) So she gives her friends Albert and Bernard a list of 10 possible birthday dates: May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15 or August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. We then have a conversation which progresses as below - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too. Bernard: At first I don't [sic] know when Cheryl's birthday is, but I know now. Albert: Then I also know when Cheryl's birthday is. So, it is possible to deduce Cheryl's birthday? I'm surprised this was not posted here before. Its become fairly popular recently. Of course, try to solve it without searching on the internet! Not much fun otherwise. :D
Mobile Apps - Sound Meter | Color Analyzer | SMBC | Football Doodles
I still don't see how to eliminate August 15 or August 17. At the point Albert says Bernard doesn't know, It eliminates May and June. Bernards revelation that he knows only eliminates any that are the 14th. But his statement can be true for any of the remaining three dates. Bernard, in fact, WOULD know at this point because there is only one month left for each of the remaining numbers that Cheryl could have told him (15, 16, or 17). Albert's final statement is merely a "hope" that he knows. He is guessing that because one of his months only has one day left that that is the month, but it could in fact be one of the August days, still. The way to fix this would be to also include July 15 and July 17 in the list of possible dates. Any comments? Did I miss something?
Brent
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I still don't see how to eliminate August 15 or August 17. At the point Albert says Bernard doesn't know, It eliminates May and June. Bernards revelation that he knows only eliminates any that are the 14th. But his statement can be true for any of the remaining three dates. Bernard, in fact, WOULD know at this point because there is only one month left for each of the remaining numbers that Cheryl could have told him (15, 16, or 17). Albert's final statement is merely a "hope" that he knows. He is guessing that because one of his months only has one day left that that is the month, but it could in fact be one of the August days, still. The way to fix this would be to also include July 15 and July 17 in the list of possible dates. Any comments? Did I miss something?
Brent
Albert was told the correct month. So if he was told August, he couldn't say that he knows. That he can say confidently at the end that he knows the date, can only mean he was told July (assuming of course neither of the two was lying).
The good thing about pessimism is, that you are always either right or pleasently surprised.
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Albert was told the correct month. So if he was told August, he couldn't say that he knows. That he can say confidently at the end that he knows the date, can only mean he was told July (assuming of course neither of the two was lying).
The good thing about pessimism is, that you are always either right or pleasently surprised.
But that is my question. How can he "say confidently" when there is still a chance it could be August? The prior quotes can and are perfectly accurate, but Albert's final comment cannot be. Unless the narrator wants to add "And he was correct" to the end of that line.
Brent
