1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Find the next element in the list

  1. Aug 23, 2015 #1
    The problem https://i.gyazo.com/66f03e2caa6ee751adc02e3535287e74.png

    Find the next element in the list

    List 1: 2, 4, 8, 16, 32
    List 2: 1, 4, 9, 16, 25
    List 3: 1, 4, 7, 10
    List 4: J, F, M, A, M, J
    List 5: Symbols, see photo


    My approaches

    List 1: This one seemed obvious. Any given element is the previous element times 2

    List 2: Another easy one. It's a list of perfect squares

    List 3: I think this one is simple. The next element is the previous element plus 3

    List 4: This is where I started to have problems. I thought maybe each letter corresponded with it's place in the alphabet, but this doesn't result in any pattern that I'm able to decipher.
    J=10
    A= 1
    F= 6
    M=13
    10, 6, 13, 1, 13, 10

    List 5: This was the other list that gave me trouble. It seems that the line at the bottom of the first two symbols moves upward. Other than that, I don't see a unifying pattern.

    List 6: Forgot to list this one when I first posted.
    O, T, T, F, F, S, S, E
     
    Last edited: Aug 23, 2015
  2. jcsd
  3. Aug 23, 2015 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    For #4, January, February, March, April, May, June, ?

    The one just before, which you did not mention, is the same idea: OTTFFSSEN. (123456789)
     
  4. Aug 23, 2015 #3

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    I would have preferred Halls had not provided the answers straight off. It would have been a gentler hint just to say that each is the initial letters of a standard sequence of words.
    For the pictorial one, do you notice a property that all of the pictures share? What happens if you 'undo' that property?
     
  5. Aug 23, 2015 #4
    Now I see that all of the pictures are symmetrical. Is it that each figure takes half of the previous figure and realigns it into a new image?
     
  6. Aug 23, 2015 #5

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Symmetry is the key, but not in the way you suggest. Since they all exhibit the same symmetry, that symmetry might not be interesting in finding the sequence. How might you 'undo' the symmetry?
     
  7. Aug 23, 2015 #6
    Adding to the figure could make it asymmetrical. As would tilting it to move the line of symmetry.
     
  8. Aug 24, 2015 #7

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Not either of those. I carefully said 'undo' rather than 'destroy'. Given some plane figure, how might you give it the bilateral symmetry in these figures without losing any information? (A certain common piece of equipment would do it.)
     
  9. Aug 28, 2015 #8

    DEvens

    User Avatar
    Education Advisor
    Gold Member

    Heh, somebody here does not watch the Simpsons regularly. Lisa Simpson took an entire episode to get the next in List 5.

    Also, it appeared in one of the later seasons of Stargate.

    Heh. As long as we are doing brain teasers: Can you think of a sequence of proper English words that would take one minute to speak normally, in which the proper spelling does not include the letter "A"?
     
  10. Aug 28, 2015 #9

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Interesting, I'd never noticed that. It seems so unlikely, much less than one in a hundred.
     
  11. Aug 31, 2015 #10

    DEvens

    User Avatar
    Education Advisor
    Gold Member

    Let me count from one to one hundred: one two three four ... one hundred.

    If you speak this in a normal way it will take about one minute. And guess what isn't in there.
     
  12. Aug 31, 2015 #11

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Yes, I understood. I was trying to indicate that without giving away the answer.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Find the next element in the list
  1. My next step (Replies: 4)

  2. Permutation List (Replies: 8)

  3. What to do next? (Replies: 5)

  4. No. of elements (Replies: 5)

Loading...