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One of These Things is Not Like the Others

  1. Nov 6, 2009 #1
    Struggling with this one. What do you think?

    Which of the five figures does not share the same basic, common feature that the others share?

    http://img12.imageshack.us/img12/7317/spatial1.png [Broken]

    The figures aren't perfectly recreated in the image - assume that the shape in the middle is a perfect square and is centered inside another perfect square.


    EDIT: image fixed. Terribly sorry for the goof.


    Also, if this stimulates interest, I've got another I can post.
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Nov 6, 2009 #2

    Jonathan Scott

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    I think the feature is ...
    symmetry
     
  4. Nov 6, 2009 #3
    Meaning they're all asymmetric except for B?
     
  5. Nov 6, 2009 #4

    DaveC426913

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    No.
    B is rotationally symmetric. They're all symmetric except D.
     
  6. Nov 6, 2009 #5
    I'm not seeing the symmetry in A, C, and E. 2 dimensional or 3?
     
  7. Nov 6, 2009 #6

    DaveC426913

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    ??
    They're all mirror symmetry about an axis.
     
  8. Nov 6, 2009 #7
    Brain fart, nevermind. I see it.
     
  9. Nov 6, 2009 #8

    DaveC426913

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    D has no symmetry. Look again. Your brain seems to have gas :wink:
     
  10. Nov 6, 2009 #9
    This is embarrassing... I made a mistake with my image. The bottom half of D should look like the top half. I wasn't looking at my own image, I was looking at the original image in print. :redface:
     
  11. Nov 6, 2009 #10

    BobG

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    B is the only item that has lines that don't border a square (assuming overlapping squares). A, C, and E are obvious; D takes a tiny bit of diligence.
     
  12. Nov 6, 2009 #11

    Jonathan Scott

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    OK, in that case the feature is ...
    mirror symmetry, and B is the odd one out
     
  13. Nov 6, 2009 #12
    The second set of figures:

    http://img11.imageshack.us/img11/3806/spatial2.png [Broken]

    Same instructions.
     
    Last edited by a moderator: May 4, 2017
  14. Nov 6, 2009 #13

    DaveC426913

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    B is the only one that cannot be drawn in its entirety with a single, unbroken line.

    There is a quick trick to this. Some intersections contain an odd number of spokes. Ergo: endpoints of more than one line.
     
  15. Nov 6, 2009 #14
    My first guess too, but we're looking for a basic, common feature, and what's even simpler is that

    all the figures except C feature triangles.

    Or is that too simple?
     
  16. Nov 6, 2009 #15

    DaveC426913

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    Personally I think my answer is more elegant. I think the answer you gave is too ... trivial.

    You could go even simpler and say c is the only one with no diagonal lines.
     
  17. Nov 6, 2009 #16
    Personally I think yours is more elegant also. :smile:
     
  18. Nov 6, 2009 #17
    I like Dave's answer, but also couldn't an alternative answer be D following the same reasoning as for the first question?
     
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