68 95 99 rule

x = μ + (z)(σ) = 5 + (3)(2) = 11. The z -score is three. Since the mean for the standard normal distribution is zero and the standard deviation is one, then the transformation in Equation 6.2.1 produces the distribution Z ∼ N(0, 1). The value x comes from a normal distribution with mean μ and standard deviation σ. dotmaxx 99