A standard deviation is a measure of variability around a mean. If it is assumed that the observations of a given characteristic, or value, cluster around the mean in a normal fashion, the computed standard deviation has a very convenient property: 68.0 percent of the values fall within plus or minus one standard deviation from the mean; 95.5 percent of the values fall within plus or minus two standard deviations from the mean; and 99.7 percent of the values fall within plus or minus three standard deviations from the mean.
Normal distribution (polish: warjancja) represents 95% of distributions.
The normal distribution (polish: rozkład normalny) refers to a family of continuous probability distributions described by the normal equation.
The normal calculator solves common statistical problems,based on the normal distribution. The calculator computes cumulative probabilities,based on three simple inputs. Simple instructions guide you to an accurate solution,quickly and easily. If anything is unclear,frequently-asked questions and sample problems provide straightforward explanations. The calculator is free. It can be found under the Stat Tables tab,which appears in the header of every Stat Trek web page.