5.3C  Modeling using a Graphing Calculator

Mathematical Modeling using a Grapher            

  We model data using Desmos and, of course, you won't be using the computer on the AP exam or your midterm. 

   With that being said, let's start learning how to model data using our graphing calculator.

   ~  Press the STAT button

   ~  Press 1: Edit

   ~  Type the following data under L1:  2, 7, 7, 9, 10, 12

   ~  Type the following data under L2: 1.5, 2.5, 3.5, 3, 3.5, 4

   ~  Once you typed in the data, Press the STAT button

   ~  Move your cursor to CALC

   ~  Press 4: LinReg (ax + b)

   ~  A screen with the following will appear:  LinReg (ax + b), press ENTER.

   ~  The following information should appear

          y = ax + b

          a = .2379603399

          b = 1.135977337

   ~  To see the equation press Y=   then the VARS button then 5: Statistics...

   ~  You will see another window... Move your cursor to EQ, then press 1: RegEQ

   ~  The equation will now appear next to Y1 =

           Y1 = .23796033994335x + 1.1359773371104

            Of course, this equation displays all of the digits, when recording your answer round to the nearest thousandths

              Y1 = .238x + 1.136

   ~  To graph this equation, set the window so you can see the equation's graph and the data points.  Press the WINDOW button

   ~  Set the window as follows:

            Xmin = 0             Xmax = 20         Xscl = 1                 

            Ymin = 0             Ymax = 10          Yscl = 1          Xres = 1

   ~   Another way to graph the equation and the data points is to press the following button: 

     ZOOM, then press 9: ZoomStat  (We'll use this key when we work with exponential modeling)

  ~  Press the GRAPH button.   You should now see the data plotted along with the graph of the equation.

  ~   If the data wasn't plotted, do the following:  Press the 2nd button and Y =

  ~   Press 5: PlotsOn

  ~   Press the GRAPH button to see the graph of the equation and its data points.