In this video, Salman Khan of Khan Academy explains standard deviation.
Khan Academy

In this video, Salman Khan of Khan Academy explains variance of a population.
Khan Academy

This video includes sample exercises and stepbystep explanations of mean and standard deviation for the California Standards Test.
Khan Academy

Interest compounded yearly, monthly, daily, etc.
About.com: Mathematics

In this video, Salman Khan of Khan Academy explains the normal distribution.
Khan Academy

In this video, Salman Khan of Khan Academy explains binomial distribution. Part 2 of 4.
Khan Academy

In this video, Salman Khan of Khan Academy explains binomial distribution. Part 1 of 4.
Khan Academy

In this video, Salman Khan of Khan Academy explains alternate variance formulas.
Khan Academy

In this video, Salman Khan of Khan Academy explains sample variance.
Khan Academy

In this video, Salman Khan of Khan Academy explains sample and population means.
Khan Academy
