AAA Math
Aaa Math: Central Tendencies Notes
A complete description of mean, median and mode. Interactive games and practice exercises are included.
Palomar Community College District
Palomar College: Mode, Median, Mean Examples
A series of step-by-step worked problems demonstrating how to take a set of data and produce the measures of central tendency. Hints are provided along the way and the final measures are shown for the user to check.
University of Glasgow
Steps Statistics Glossary: Sample Mean
The definition of a sample mean is provided along with the symbol commonly used for it and an example to show the formula in action. A link to "expected value" - a related topic - is provided.