Results 1 to 6 of 6
Like Tree2Thanks
  • 1 Post By helpneeded22
  • 1 Post By peysy

Math Help - Next Number in the Sequence

  1. #1
    Newbie
    Joined
    Aug 2013
    From
    Canada
    Posts
    2
    Thanks
    1

    Next Number in the Sequence

    I am reviewing a cognitive skills test and I am unable to determine the next number in given sequences. After looking at the answers, I am still unable to identify the sequences. Could someone with better cognitive skills than I, please tell me what the sequences are:

    Question 1: What is the rule that has been used to produce this series?

    10, 14, 11, 18, 18, 22,

    The next number in the sequence is:
    Spoiler:
    19



    Question 2:
    What is the rule that has been used to produce this series?

    1, 3, 9, 2, 8, 32, 3,

    The next number in the sequence is:
    Spoiler:
    15
    Last edited by helpneeded22; August 19th 2013 at 08:45 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Aug 2013
    From
    Canada
    Posts
    2
    Thanks
    1

    Re: Next Number in the Sequence

    Well, I finally figured out #2. Basically each series is a set of 3 numbers. The first 2 numbers of the 3 numbers is multiplied by an incrementing number. (1 x 3 = 3, 3 x 3 = 9) and then (2 x 4 = 8, 8 x 4 = 32) The next number if the sequence would then be: (3 x 5 =15, 15 x 5 = 75).

    I'm still stumped on #1 though.
    Last edited by helpneeded22; August 19th 2013 at 09:46 PM.
    Thanks from emakarov
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Dec 2012
    From
    the Urals
    Posts
    10
    Thanks
    2

    Re: Next Number in the Sequence

    10+14+11+18=53
    14+11+18+18=61
    11+18+18+22=69
    18+18+22+x=77
    x=19
    Thanks from emakarov
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Aug 2013
    From
    Derby, UK
    Posts
    1

    Re: Next Number in the Sequence

    I'm still baffled soes someone want to explain the first one to me?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    Joined
    Oct 2009
    Posts
    5,559
    Thanks
    785

    Re: Next Number in the Sequence

    Quote Originally Posted by keypoint View Post
    soes someone want to explain the first one to me?
    If we denote the sequence by a1, a2, .... then the property that peysy found is that ak + ak+1 + ak+2 + ak+3 = 45 + 8k for all k >= 1. So, ak+3 can be expressed through previous elements as follows: ak+3 = (45 + 8k) - (ak + ak+1 + ak+2). For k = 4 one gets ak+3 = a7 = 77 - a4 - a5 - a6 = 77 - 18 - 18 - 22 = 19.

    Amazing find. I don't like such problems. though, because it is easy to write a polynomial f(x) that equals given numbers for x = 1, 2, 3, ..., 6 and equals any number for x = 7.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Member
    Joined
    Sep 2012
    From
    Planet Earth
    Posts
    196
    Thanks
    49

    Re: Next Number in the Sequence

    True, it ultimately depends on what would be considered the "most obvious" or "least arbitrary" pattern, but that is a matter of opinion. For any given sequence of numbers like this, the next number can be anything and still satisfy what some people would consider an aesthetically pleasing pattern.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Number Sequence! Help!
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: April 16th 2013, 12:26 PM
  2. number sequence vs number sentence
    Posted in the Math Topics Forum
    Replies: 6
    Last Post: January 17th 2013, 06:42 AM
  3. The number e as a sequence
    Posted in the Calculus Forum
    Replies: 4
    Last Post: June 28th 2011, 09:44 AM
  4. Number Sequence
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: May 10th 2011, 08:03 AM
  5. Number Sequence
    Posted in the Math Challenge Problems Forum
    Replies: 0
    Last Post: July 3rd 2006, 08:38 AM

Search Tags


/mathhelpforum @mathhelpforum