Empirical Rule Calculator,68-95-99 Rule – Normal Distribution Explained in Plain English,The 68-95-99.7 rule! The 68-95-99.7 rule, also known as the three sigma rule, describes the distribution of data in a normal distribution: approximately 68% falls within one standard deviation from ,Empirical Rule: Definition, Formula, Example, How It's Used,Empirical Rule: Definition, Formula, Example, How It's Used,