1. Press the Y= key and clear any equations.
2. Press the STAT key, use the arrow keys to select EDIT, and enter this data:
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These data points represent the height of a model rocket at various times during its flight after its rocket motor has burned out. The numbers under the L1 heading are the seconds since the rocket was launched. The numbers under the L2 heading are the height of the rocket in feet.
3. Press the STAT key, select CALC, and choose option number 5: QuadReg. This will bring you back to the home screen, with QuadReg showing. Type "L1, L2" by pressing 2nd and 1, then comma, then 2nd and 2. Type "Y1" by pressing VARS, moving across to Y-VARS, choosing Function, and choosing option number 1. Your home screen should show:
QuadReg L1, L2, Y1
Now press ENTER. You will see something like:
y = ax2 +bx + c
a = -15.35714286
b = 121.0714286
c = 125.7142857
The variables a , b, and c are the coefficients for the quadratic equation that best fits the data you entered.
4. Press the StatPlot key (2nd and Y=). Choose Plot1 and press ENTER. Set the options as follows:
On
Type
Scatter
(the first icon)
Xlist
L1
Ylist
L2
Mark
Box
(the first icon)
5. Press the WINDOW key and enter the following:
Xmin
0
Xmax
10
Xscl
2
Ymin
0
Ymax
400
Yscl
100
These numbers will tell the graphing calculator what part of the graph it should display. When you do a stat plot, you need to look at your data and choose values that will include your data. You can let the calculator choose these values for you by pressing the ZOOM key and choosing option number 9: ZOOMSTAT.
6. Press the GRAPH key. The graph will show the individual data points as well as the best fit parabola. Press the TRACE key and use the arrow keys to predict when the rocket will be at various heights (you may need to use the up arrow key to trace the parabola).
When did the rocket reach its maximum height?
What was the rocket's maximum height?
When will the rocket hit the ground?
Although the rocket was in fact launched from ground level at time 0, the graph seems to indicate that the rocket was launched at about time -1 seconds. What is the limitation of this model?