Click on the following links. Please note these will open in a new window.

Basic Probability
https://www.youtube.com/watch?v=-8eSOmTPUbk
Introduction to probability

Normal Distribution and Z Score
https://www.youtube.com/watch?v=SwKhknbhWsc
Stats: Percentile, z-score, and Area Under Normal Curve

https://www.youtube.com/watch?v=ER-e1wwhjXY
Stats: Finding Z-value Given the Probability