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  3. Mathematicians - Treat for the weekend / might drive you crazy

Mathematicians - Treat for the weekend / might drive you crazy

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  • R Raj Lal

    The answer to everything but this one :) No explanation ??? The solution is so simple that it will explain everything and everything fits into the picture perfectly like a jigsaw puzzle "Not everything that counts can be counted..." -Albert Einstein

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    ColinDavies
    wrote on last edited by
    #10

    explanations are for sissys Regardz Colin J Davies The most LinkedIn CPian (that I know of anyhow) :-)

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    • R Raj Lal

      (Actually, This is an old problem but just to stop smartsy CPians from using the word "nanosecond" forever let's blast them with it! ). There are 2 integers a and b (Though programmers like i and j more as integers) And two CPian A and B. (The result will decide who are they) Rules of the game ------------------------------- I. 2 <= a,b <= 100 II. A is told the product of a and b III. B is told the sum of a and b. IV. Neither is told the values The cPians conversation ::: ------------------------------- 1=> B: I cannot determine a, b. 2=> A: I cannot determine a, b 3=> B: I already knew that. 4=> A: In that case, I now know them 5=> B: In that case, I too now know a, b. What are the numbers ??? ------------------------------- Is'nt it simple and beautiful ? I can hear you saying " huh! " cheers. "Not everything that counts can be counted..." -Albert Einstein

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      ColinDavies
      wrote on last edited by
      #11

      Interpreting your qu differently gives 4, 13. I think this used to be called "the impossible problem" Regardz Colin J Davies The most LinkedIn CPian (that I know of anyhow) :-)

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      • C ColinDavies

        explanations are for sissys Regardz Colin J Davies The most LinkedIn CPian (that I know of anyhow) :-)

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        Raj Lal
        wrote on last edited by
        #12

        Guessing two numbers between 2 and 100, gives a probability of 0.02020202020202020202020202020201 chances of getting it correct so it is not. As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.-Albert Einstein

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        • R Raj Lal

          Guessing two numbers between 2 and 100, gives a probability of 0.02020202020202020202020202020201 chances of getting it correct so it is not. As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.-Albert Einstein

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          ColinDavies
          wrote on last edited by
          #13

          I believe its abit less than that. Regardz Colin J Davies The most LinkedIn CPian (that I know of anyhow) :-)

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          • R Raj Lal

            (Actually, This is an old problem but just to stop smartsy CPians from using the word "nanosecond" forever let's blast them with it! ). There are 2 integers a and b (Though programmers like i and j more as integers) And two CPian A and B. (The result will decide who are they) Rules of the game ------------------------------- I. 2 <= a,b <= 100 II. A is told the product of a and b III. B is told the sum of a and b. IV. Neither is told the values The cPians conversation ::: ------------------------------- 1=> B: I cannot determine a, b. 2=> A: I cannot determine a, b 3=> B: I already knew that. 4=> A: In that case, I now know them 5=> B: In that case, I too now know a, b. What are the numbers ??? ------------------------------- Is'nt it simple and beautiful ? I can hear you saying " huh! " cheers. "Not everything that counts can be counted..." -Albert Einstein

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            Gary R Wheeler
            wrote on last edited by
            #14

            OK, your post has been up for several hours now. How about posting your solution? Personally, I think the problem is indeterminate, at least without additional constraints.


            Software Zen: delete this;

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            • R Raj Lal

              (Actually, This is an old problem but just to stop smartsy CPians from using the word "nanosecond" forever let's blast them with it! ). There are 2 integers a and b (Though programmers like i and j more as integers) And two CPian A and B. (The result will decide who are they) Rules of the game ------------------------------- I. 2 <= a,b <= 100 II. A is told the product of a and b III. B is told the sum of a and b. IV. Neither is told the values The cPians conversation ::: ------------------------------- 1=> B: I cannot determine a, b. 2=> A: I cannot determine a, b 3=> B: I already knew that. 4=> A: In that case, I now know them 5=> B: In that case, I too now know a, b. What are the numbers ??? ------------------------------- Is'nt it simple and beautiful ? I can hear you saying " huh! " cheers. "Not everything that counts can be counted..." -Albert Einstein

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              leppie
              wrote on last edited by
              #15

              2 & 3 or vica versa My reasoning the lowest 2 numbers that are not 2 & 2. 1. B: (a x b) = 6 2. A: (a + b) = 5 3. B: a != b and a < 4 and b < 4 4. A: Can only be 2 & 3 5: B: Can only be 2 & 3 :confused: Probably very incorrect... :p [update] Similar to Rui A. Rebelo's solution [update] xacc.ide-0.1-rc3 released! Download and screenshots -- modified at 12:23 Saturday 12th November, 2005

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              • C ColinDavies

                I believe its abit less than that. Regardz Colin J Davies The most LinkedIn CPian (that I know of anyhow) :-)

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                p daddy
                wrote on last edited by
                #16

                I liked the 6 and 7 answer - it is indeed the answer to everything.... Paul

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                • R Raj Lal

                  (Actually, This is an old problem but just to stop smartsy CPians from using the word "nanosecond" forever let's blast them with it! ). There are 2 integers a and b (Though programmers like i and j more as integers) And two CPian A and B. (The result will decide who are they) Rules of the game ------------------------------- I. 2 <= a,b <= 100 II. A is told the product of a and b III. B is told the sum of a and b. IV. Neither is told the values The cPians conversation ::: ------------------------------- 1=> B: I cannot determine a, b. 2=> A: I cannot determine a, b 3=> B: I already knew that. 4=> A: In that case, I now know them 5=> B: In that case, I too now know a, b. What are the numbers ??? ------------------------------- Is'nt it simple and beautiful ? I can hear you saying " huh! " cheers. "Not everything that counts can be counted..." -Albert Einstein

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                  Raj Lal
                  wrote on last edited by
                  #17

                  For those who are still trying for the solution here is a clue to drive you more crazy 3=> B: I already knew that. i will post the solution by tonight "Not everything that counts can be counted..." -Albert Einstein

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                  • L leppie

                    2 & 3 or vica versa My reasoning the lowest 2 numbers that are not 2 & 2. 1. B: (a x b) = 6 2. A: (a + b) = 5 3. B: a != b and a < 4 and b < 4 4. A: Can only be 2 & 3 5: B: Can only be 2 & 3 :confused: Probably very incorrect... :p [update] Similar to Rui A. Rebelo's solution [update] xacc.ide-0.1-rc3 released! Download and screenshots -- modified at 12:23 Saturday 12th November, 2005

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                    Raj Lal
                    wrote on last edited by
                    #18

                    Check the clue below that can filter the range of numbers its better to try the other way (backward :) ) "Not everything that counts can be counted..." -Albert Einstein

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                    • G Gary R Wheeler

                      OK, your post has been up for several hours now. How about posting your solution? Personally, I think the problem is indeterminate, at least without additional constraints.


                      Software Zen: delete this;

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                      Raj Lal
                      wrote on last edited by
                      #19

                      Check the clue below that can filter the range of numbers its better to try the other way (backward :) ) I don't like to keep you waiting but some people are still trying. I will post the solution tonight. May be before that you might hit the light bulb moment :) "Not everything that counts can be counted..." -Albert Einstein

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                      • R Raj Lal

                        For those who are still trying for the solution here is a clue to drive you more crazy 3=> B: I already knew that. i will post the solution by tonight "Not everything that counts can be counted..." -Albert Einstein

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                        leppie
                        wrote on last edited by
                        #20

                        Is A and B necesary CPians? Or can they be other kinds of people too? If the former, my original hunch was perhaps the user id of 2 specific users under 10000 that can be broken down to the requirements... (long shot :) ) xacc.ide-0.1-rc3 released! Download and screenshots

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                        • L leppie

                          Is A and B necesary CPians? Or can they be other kinds of people too? If the former, my original hunch was perhaps the user id of 2 specific users under 10000 that can be broken down to the requirements... (long shot :) ) xacc.ide-0.1-rc3 released! Download and screenshots

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                          Raj Lal
                          wrote on last edited by
                          #21

                          looooong shot... No, i added it just to make it look more homely :-D "Not everything that counts can be counted..." -Albert Einstein

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                          • R Raj Lal

                            (Actually, This is an old problem but just to stop smartsy CPians from using the word "nanosecond" forever let's blast them with it! ). There are 2 integers a and b (Though programmers like i and j more as integers) And two CPian A and B. (The result will decide who are they) Rules of the game ------------------------------- I. 2 <= a,b <= 100 II. A is told the product of a and b III. B is told the sum of a and b. IV. Neither is told the values The cPians conversation ::: ------------------------------- 1=> B: I cannot determine a, b. 2=> A: I cannot determine a, b 3=> B: I already knew that. 4=> A: In that case, I now know them 5=> B: In that case, I too now know a, b. What are the numbers ??? ------------------------------- Is'nt it simple and beautiful ? I can hear you saying " huh! " cheers. "Not everything that counts can be counted..." -Albert Einstein

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                            David ONeil
                            wrote on last edited by
                            #22

                            Is there more than one answer?

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                            • D David ONeil

                              Is there more than one answer?

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                              Raj Lal
                              wrote on last edited by
                              #23

                              only one i presume "Not everything that counts can be counted..." -Albert Einstein

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                              • R Raj Lal

                                only one i presume "Not everything that counts can be counted..." -Albert Einstein

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                                David ONeil
                                wrote on last edited by
                                #24

                                You presume? Please see my email to you, and then clarify your presumption. Thanks, David

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                                • D David ONeil

                                  You presume? Please see my email to you, and then clarify your presumption. Thanks, David

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                                  Raj Lal
                                  wrote on last edited by
                                  #25

                                  thanks for the link actually i got what you are saying its the domain which is not mentioned there. If the Domain is 2 to 100 ( which is in this case ) then there is a unique solution If you expand the domain to 2 to 1000 then the there are two solutions :) the problem you sent the link it does not gives any MAX Range only thing it gives is the MIN Range

                                  The Link says:

                                  PUZZLE STATEMENT: A and B are positive integers greater than 1.B Professor Sum "S" knows only the sum of A and B. Professor Product "P" knows only the product of A and B. The following conversation occurs between "S" and "P" "S" says to "P": You don't know A and B. "P" says to "S": Now I do know A and B. "S" says to "P": Now I know A and B as well. What are the values of A and B?

                                  SO TWO SOLUTIONS THERE but in our problem there is only one :) So i think that removes the ambiguity About wraping it the cache page says the problem was

                                  The Link also have:

                                  Assigned: Wednesday, Sept. 25, 2002 Due: Thursday, Oct. 10, 2002

                                  So i think that makes it clear :) , by the way i liked to see that it was an assignment because to find a solution u need to do some exhaust search with some constraints. Cheers "Not everything that counts can be counted..." -Albert Einstein

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                                  • R Raj Lal

                                    thanks for the link actually i got what you are saying its the domain which is not mentioned there. If the Domain is 2 to 100 ( which is in this case ) then there is a unique solution If you expand the domain to 2 to 1000 then the there are two solutions :) the problem you sent the link it does not gives any MAX Range only thing it gives is the MIN Range

                                    The Link says:

                                    PUZZLE STATEMENT: A and B are positive integers greater than 1.B Professor Sum "S" knows only the sum of A and B. Professor Product "P" knows only the product of A and B. The following conversation occurs between "S" and "P" "S" says to "P": You don't know A and B. "P" says to "S": Now I do know A and B. "S" says to "P": Now I know A and B as well. What are the values of A and B?

                                    SO TWO SOLUTIONS THERE but in our problem there is only one :) So i think that removes the ambiguity About wraping it the cache page says the problem was

                                    The Link also have:

                                    Assigned: Wednesday, Sept. 25, 2002 Due: Thursday, Oct. 10, 2002

                                    So i think that makes it clear :) , by the way i liked to see that it was an assignment because to find a solution u need to do some exhaust search with some constraints. Cheers "Not everything that counts can be counted..." -Albert Einstein

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                                    David ONeil
                                    wrote on last edited by
                                    #26

                                    As I pointed out in my email, that page gives two solutions where the numbers are both under 100, therefore, as you worded it, it is an ambiguous problem, unless the page is incorrect? David

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                                    • D David ONeil

                                      As I pointed out in my email, that page gives two solutions where the numbers are both under 100, therefore, as you worded it, it is an ambiguous problem, unless the page is incorrect? David

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                                      Raj Lal
                                      wrote on last edited by
                                      #27

                                      Well , i try to clearify The Domain actually restricts the unique solution though i understand both the solutions is in the range and that makes it feel that both are correct. but the solution space is not so its not what it looks like , if the solution space is 2 - 100 you will never get the other solution unanimously. and ALSO it contradicts the problem it self becuse if there are two solutions then how come the the two persons are sure about the anwser they will still have to decide between the two solutions right ? I just wrote this without thninking -- modified at 19:18 Sunday 13th November, 2005

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                                      • R Raj Lal

                                        Well , i try to clearify The Domain actually restricts the unique solution though i understand both the solutions is in the range and that makes it feel that both are correct. but the solution space is not so its not what it looks like , if the solution space is 2 - 100 you will never get the other solution unanimously. and ALSO it contradicts the problem it self becuse if there are two solutions then how come the the two persons are sure about the anwser they will still have to decide between the two solutions right ? I just wrote this without thninking -- modified at 19:18 Sunday 13th November, 2005

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                                        David ONeil
                                        wrote on last edited by
                                        #28

                                        You are being unclear.

                                        Quartz... wrote:

                                        but the solution space is not so its not what it looks like , if the solution space is 2 - 100 you will never get the other solution unanimously.

                                        I think you meant "if the solution space is 2 - 100 you will never get the other solution by itself." Yet both the solutions occur 'by themselves' in the solutions given in that page, and I cannot see ANY difference in the solution spaces between your posting of the problem and the posting on that page.

                                        and ALSO it contradicts the problem it self becuse if there are two solutions then how come the the two persons are sure about the anwser they will still have to decide between the two solutions right ?

                                        Wrong. Each of them has a clue to the answer, and when A knows the answer, the answer becomes unambiguous to B based upon B's information.

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                                        • D David ONeil

                                          You are being unclear.

                                          Quartz... wrote:

                                          but the solution space is not so its not what it looks like , if the solution space is 2 - 100 you will never get the other solution unanimously.

                                          I think you meant "if the solution space is 2 - 100 you will never get the other solution by itself." Yet both the solutions occur 'by themselves' in the solutions given in that page, and I cannot see ANY difference in the solution spaces between your posting of the problem and the posting on that page.

                                          and ALSO it contradicts the problem it self becuse if there are two solutions then how come the the two persons are sure about the anwser they will still have to decide between the two solutions right ?

                                          Wrong. Each of them has a clue to the answer, and when A knows the answer, the answer becomes unambiguous to B based upon B's information.

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                                          Raj Lal
                                          wrote on last edited by
                                          #29

                                          There is a slight difference in the question itself The Problem given in that page is

                                          A and B are positive integers greater than 1 ( there is no upper limit )

                                          And the Problem here is

                                          2 >= a,b ** >= 100**

                                          I think thats the ony difference which filters out the second solution I am compilng the solution with a detailed explaination hope it will clearify it, sorry if i got you confused "Not everything that counts can be counted..." -Albert Einstein

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