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  3. When is Cheryl's Birthday?

When is Cheryl's Birthday?

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  • A Abhinav S

    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

    A Offline
    A Offline
    Agent__007
    wrote on last edited by
    #2

    July 16. :rolleyes:

    You have just been Sharapova'd.

    P 1 Reply Last reply
    0
    • A Abhinav S

      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

      S Offline
      S Offline
      Stefto
      wrote on last edited by
      #3

      Yes.

      Life's like a nose, you've got to get out of it whats in it!

      1 Reply Last reply
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      • A Agent__007

        July 16. :rolleyes:

        You have just been Sharapova'd.

        P Offline
        P Offline
        Pirate Guy
        wrote on last edited by
        #4

        I could tell the answer just by looking at the problem - "Cheryl's Birthday". :laugh:

        I ain't got no signature.

        1 Reply Last reply
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        • A Abhinav S

          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

          L Offline
          L Offline
          Lost User
          wrote on last edited by
          #5

          Yes || No || Maybe

          How do we preserve the wisdom men will need, when their violent passions are spent? - The Lost Horizon

          1 Reply Last reply
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          • A Abhinav S

            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

            D Offline
            D Offline
            Dennis_E
            wrote on last edited by
            #6

            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? ;)

            L OriginalGriffO S 4 Replies Last reply
            0
            • A Abhinav S

              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

              L Offline
              L Offline
              Lost User
              wrote on last edited by
              #7

              June 17 - ignore this, got Albert and Bernard wrong way round :(

              One day I aspire to having a signature.

              1 Reply Last reply
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              • D Dennis_E

                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? ;)

                L Offline
                L Offline
                Lost User
                wrote on last edited by
                #8

                Researching into time travel? Actually baby not born yet so probably just unaware.

                One day I aspire to having a signature.

                1 Reply Last reply
                0
                • D Dennis_E

                  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? ;)

                  OriginalGriffO Offline
                  OriginalGriffO Offline
                  OriginalGriff
                  wrote on last edited by
                  #9

                  In jail, I hope...

                  Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                  "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
                  "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

                  D 1 Reply Last reply
                  0
                  • A Abhinav S

                    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

                    W Offline
                    W Offline
                    W Balboos GHB
                    wrote on last edited by
                    #10

                    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

                    9 1 Reply Last reply
                    0
                    • OriginalGriffO OriginalGriff

                      In jail, I hope...

                      Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                      D Offline
                      D Offline
                      Dennis_E
                      wrote on last edited by
                      #11

                      Someone else told me the same answer once. He made a mistake in his calculation. I guess you did too.

                      OriginalGriffO 1 Reply Last reply
                      0
                      • D Dennis_E

                        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? ;)

                        S Offline
                        S Offline
                        szukuro
                        wrote on last edited by
                        #12

                        I guess the answer you're looking for is "in her" ;P (She's 20y3m old and the "baby" -9m)

                        1 Reply Last reply
                        0
                        • D Dennis_E

                          Someone else told me the same answer once. He made a mistake in his calculation. I guess you did too.

                          OriginalGriffO Offline
                          OriginalGriffO Offline
                          OriginalGriff
                          wrote on last edited by
                          #13

                          Nah - I just don't like the guy... :laugh:

                          Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

                          "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
                          "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

                          1 Reply Last reply
                          0
                          • D Dennis_E

                            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? ;)

                            L Offline
                            L Offline
                            Lost User
                            wrote on last edited by
                            #14

                            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).

                            1 Reply Last reply
                            0
                            • A Abhinav S

                              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

                              Mike HankeyM Offline
                              Mike HankeyM Offline
                              Mike Hankey
                              wrote on last edited by
                              #15

                              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!

                              R 1 Reply Last reply
                              0
                              • A Abhinav S

                                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

                                R Offline
                                R Offline
                                Rage
                                wrote on last edited by
                                #16

                                Now this is the Cheryl on the cake.

                                Do not escape reality : improve reality !

                                1 Reply Last reply
                                0
                                • Mike HankeyM Mike Hankey

                                  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!

                                  R Offline
                                  R Offline
                                  Rage
                                  wrote on last edited by
                                  #17

                                  Jokers are not allowed, not even this one.

                                  Do not escape reality : improve reality !

                                  1 Reply Last reply
                                  0
                                  • A Abhinav S

                                    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

                                    K Offline
                                    K Offline
                                    Kevin Marois
                                    wrote on last edited by
                                    #18

                                    Helping your kid with their Common core again?

                                    If it's not broken, fix it until it is

                                    1 Reply Last reply
                                    0
                                    • W W Balboos GHB

                                      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

                                      9 Offline
                                      9 Offline
                                      9082365
                                      wrote on last edited by
                                      #19

                                      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.

                                      W 1 Reply Last reply
                                      0
                                      • 9 9082365

                                        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.

                                        W Offline
                                        W Offline
                                        W Balboos GHB
                                        wrote on last edited by
                                        #20

                                        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

                                        9 1 Reply Last reply
                                        0
                                        • W W Balboos GHB

                                          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

                                          9 Offline
                                          9 Offline
                                          9082365
                                          wrote on last edited by
                                          #21

                                          Well, yeah, except it was simply a clerical error. The papers for the two age groups were prepared together and the question was inadvertently transposed. As usual cock-up was always far more likely to be the explanation than conspiracy!

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