Calculator Notes for TI-89, TI-92 Plus, and Voyage 200

Note 13C • Probabilities of Normal Distributions (continued) TI-89/TI-92 Plus/Voyage 200
Before using the command, first enter the equation of the normal curve into
the Y Editor screen. (See Note 13B.) Then on the Home screen, enter the
integration command in the form ∫(y1(x),x,lower, upper).
Graphing Ranges
The calculator does not have a command that automatically draws a normal
curve and shades the area under it. The best you can do is calculate the area,
as explained above, and then graph a system of inequalities that shows the
area as a feasible region. (Review Note 6G for help with graphing
inequalities.)
Your system should include these four equations:
y1 the equation of your normal curve. Shade above y1.
y2 0. Shade below y2.
y3 1000(lowerx). Shade below y3.
y4 1000(upperx). Shade above y4.
[2.7, 3.5, 0.1, 0.5, 3, 0]
Probabilities of Normal Distributions with the Stats/List Editor
If your calculator has the Stats/List Editor application, you can use built-in
functions that calculate and graph the area under a normal curve. To run the
Stats/List Editor, press APPS 1:FlashApps and select Stats/List Editor.
The normal cumulative distribution function, Normal Cdf, calculates the
area between two endpoints. You find the Normal Cdf command by pressing
F5 (Distr) 4:Normal Cdf. Enter the Lower Value, the Upper Value, the mean, and the
standard deviation, and then press ENTER .
Discovering Advanced Algebra Calculator Notes for the Texas Instruments TI-89, TI-92 Plus, and Voyage 200 CHAPTER 13 77
©2004 Key Curriculum Press
(continued)