1. Normal Distribution

http://www.mathsisfun.com/data/standard-normal-distribution.html

2. LogNormalDistribution

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Log-normal_distribution.html

3. Mean, Median and Mode

https://www.khanacademy.org/math/probability/descriptive-statistics/central_tendency/v/statistics-intro–mean–median-and-mode