Results 1 to 7 of 7

Math Help - Logic problem

  1. #1
    Banned
    Joined
    Oct 2009
    Posts
    769

    Logic problem

    Two perfect logicians, S and P, are told that integers x and y have been chosen such that 1 < x < y and x+y < 100. S is given the value x+y and P is given the value xy. They then have the following conversation.
    P: I cannot determine the two numbers.
    S: I knew that.
    P: Now I can determine them.
    S: So can I.
    Given that the above statements are true, what are the two numbers? (computer assistance is allowed.)



    Moderator edit: Apporved Challenge question.
    Last edited by mr fantastic; December 3rd 2010 at 11:07 AM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by wonderboy1953 View Post
    Two perfect logicians, S and P, are told that integers x and y have been chosen such that 1 < x < y and x+y < 100. S is given the value x+y and P is given the value xy. They then have the following conversation.
    P: I cannot determine the two numbers.
    S: I knew that.
    P: Now I can determine them.
    S: So can I.
    Given that the above statements are true, what are the two numbers? (computer assistance is allowed.)



    Moderator edit: Apporved Challenge question.
    P: I cannot determine the two numbers. - the number I have is not the product of two primes

    S: I knew that. - the sum I have cannot be the sum of two primes

    P: Now I can determine them. - there is only one factorisation such that the sum cannot be the sum of two primes

    S: So can I. - there is only one decomposition of my number into a sum such that the sum of a factorisation of their product cannot be the sum of two primes

    CB
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,100
    Thanks
    67
    Quite a golden oldie:

    Google
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by Wilmer View Post
    Quite a golden oldie:

    Google
    I am reasonably sure that I have solved this (or a number of problems remarkably like this) before as a NewScientist Enigma.

    CB
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MSM
    MSM is offline
    Newbie
    Joined
    Dec 2010
    Posts
    2

    found a solution

    13 and 4
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Banned
    Joined
    Oct 2009
    Posts
    769
    Quote Originally Posted by MSM View Post
    13 and 4
    You're the winner (good job).
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Banned
    Joined
    Oct 2009
    Posts
    769
    Quote Originally Posted by Wilmer View Post
    Quite a golden oldie:

    Google
    An oldie but goodie (honestly I do try to post in stuff that's either hard to find or fresh).
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: October 4th 2011, 06:34 AM
  2. Help with logic problem
    Posted in the Discrete Math Forum
    Replies: 2
    Last Post: February 10th 2010, 04:37 PM
  3. Help on a problem to do with logic please
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: May 10th 2009, 12:10 AM
  4. Logic problem
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: October 24th 2007, 06:58 AM
  5. another logic problem....PLEASE HELP
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: October 21st 2007, 09:48 AM

Search Tags


/mathhelpforum @mathhelpforum