The Empirical Rule for Normal Distributions
This Demonstration illustrates the "empirical rule" for normal distributions: approximately 68% of the area under the curve falls within one standard deviation of the mean, approximately 95% within two standard deviations, and approximately 99.7% within three standard deviations. Various display options are available (see the Snapshots and the Details section).
The region under the curve is interactive. Click any region to shade or unshade it and include or exclude its area from the total.