Columbia University
Columbia University: Expected Value Pdf
A PDF explaining and giving examples to show how the expected value of a random variable indicates its weighted average.
Other
Magoosh: Statistics Fundamentals
An online course on the fundamentals of statistics including video lessons in Mean, Median, and Mode; Weighted Averages; Quartiles and Boxplots; Range and Standard Deviation; Normal Distribution; Z-scores; Intro to Inferential...
Texas Instruments
Texas Instruments: Heavy Hitting #2
This activity uses baseball's slugging average to compute weighted means using summary statistics. Some students may need an explanation of the terms singles, doubles, triples, and home runs.
Other
Stat Soft: Statistics Glossary
Dozens of statistical terms are defined and illustrated in this glossary.