Standard Normal Distribution — Properties: The "standard" normal distribution is a normal distribution whose mean is zero and where the standard deviation equals one... Area Percentage Table: Appendix Reference 7 shows the graph's area percentage values over the interval between "z = 0" and "z = b" (for any number, b > 0). Notation:  P(a < z < b) represents the Percentage of the data that lies between "z = a" and "z = b".