Determining Areas Under a Normal Curve Using Technology
C. Determining Areas Under a Normal Curve Using Technology
Using a z-score table is a good way to determine areas under a normal curve. However, as you have seen, the tables have limitations due to rounding. Fortunately, many calculators and computer programs are capable of providing the same information without the limitations.
Note that the z-score tables give area to the left of a z-score, while calculators and computers usually give area between two z-scores.
Open the Area under a Normal Curve applet (7 March 2013, Created with GeoGebra) for a program that will calculate areas for you. Instructions for how to determine areas under a normal curve using a TI-83 / TI-84 calculator can be found in Equipment Room or by clicking here. You may use the applet, your calculator, or the tables to complete your course work. However, the applet will not be available for your use during exams, so it is important that you are comfortable with at least one other method.
Move the sliders to see the area between z-scores. The left and right arrow keys can be used to make fine adjustments to the sliders.