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Who's Looking At Who?

  1. Dec 11, 2009 #1
    This is from Scientific American Mind:

    Jack is looking at Anne, and Anne is looking at George. Jack is married and George is not. Is there a married person looking at an unmarried person?

    a) Yes b) No c) Can't tell from the given information
     
    Last edited: Dec 11, 2009
  2. jcsd
  3. Dec 11, 2009 #2
    It's (a) if each is a person :) But otherwise, (c).

    DaveE
     
  4. Dec 11, 2009 #3
    Lol yes, a is correct. 90% of people choose C though because they refuse to think.
     
  5. Dec 17, 2009 #4
    No. From: "Jack is looking at Anne, and Anne is looking at George. Jack is married and George is not. Is there a married person looking at an unmarried person?"

    We have:

    Jackm --> AnneM? UM?

    AnneM? UM? --> GeorgeUM

    The options are:

    a) Yes b) No c) Can't tell from the given information

    We have no idea from this info whether Anne is married or unmarried. However, these are the only two cases.

    Case 1: If Anne is married, then Anne (married) is looking at George (unmarried)

    Case 2: If Anne is unmarried, then Jack (married) is looking at Anne (unmarried)

    So yes, the answer is (now) obviously a) Yes: A married person is looking at an unmarried person.

    Most people get hung up on the fact that they cannot tell whether it's Jack --> Anne or Anne --> George, and say, "indeterminant," when the question isn't asking who's married or unmarried, it's asking whether "a married person" (doesn't matter who) is looking at an unmarried person (also doesn't matter who).
     
    Last edited: Dec 17, 2009
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