Results 1 to 2 of 2

Math Help - Determining Line of best fit

  1. #1
    Newbie
    Joined
    Sep 2009
    Posts
    13

    Cool Determining Line of best fit

    I have to figure out the line of best fit for children's books, the following data is given.
    Recommended Age Leve - Mean Word Length
    4 - 3.5
    6 - 5.5
    5 - 4.6
    6 - 5.0
    7 - 5.2
    9 - 6.5
    8 - 6.1
    5 - 4.9
    So i went ahead and made a table for x, y, x*y, x2 and y2 then i imputed the following data. Does this look anywhere close to being right?

    Slope = n(Sigma(xy)) - (Sigma(x)) / n(Sigma(x2)) - (Sigma(x))2
    = 8(268.2) - (50)(41.3) / 8(332) - (50)2
    = 2145.6 - 2065 / 2656 - 2500
    = 80.6 / 156
    = 0.52

    Intercept = Sigma(y) - m(Sigma(x)) / n
    = 41.3 - 0.52(50) / 8
    = 1.9125

    y = mx + b
    y = 0.52x + 1.91

    then looking at this if i go to figure out what the average word length is for a 12 year-old i get 4.33... that's even less then what's recommended for a 6 year old?!?!?! Is there somewhere in here where i'm going wrong?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Mar 2009
    Posts
    133
    checked using eviews and the model is correct.

    For a 12 year old, i got 8.15=12*.52+1.91
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Determining slope of the line
    Posted in the Algebra Forum
    Replies: 1
    Last Post: November 17th 2011, 02:31 PM
  2. [SOLVED] Determining straight line characteristics for 1st order PDE's
    Posted in the Differential Equations Forum
    Replies: 6
    Last Post: August 9th 2010, 10:39 AM
  3. Replies: 1
    Last Post: February 21st 2010, 04:47 PM
  4. Replies: 2
    Last Post: February 14th 2010, 11:18 AM
  5. Replies: 2
    Last Post: March 8th 2007, 05:15 PM

Search Tags


/mathhelpforum @mathhelpforum