This marketing chart sample shows normal (Gaussian) distribution. It was designed on the base of the Wikimedia Commons file: Empirical Rule.PNG. [commons.wikimedia.org/wiki/File:Empirical_Rule.PNG]
This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license. [creativecommons.org/licenses/by-sa/4.0/deed.en]
"In probability theory, the normal (or Gaussian) distribution is a very commonly occurring continuous probability distributionâ€”a function that tells the probability that an observation in some context will fall between any two real numbers. For example, the distribution of grades on a test administered to many people is normally distributed. Normal distributions are extremely important in statistics and are often used in the natural and social sciences for real-valued random variables whose distributions are not known.
The Gaussian distribution is sometimes informally called the bell curve. However, many other distributions are bell-shaped (such as Cauchy's, Student's, and logistic). The terms Gaussian function and Gaussian bell curve are also ambiguous because they sometimes refer to multiples of the normal distribution that cannot be directly interpreted in terms of probabilities." [Normal distribution. Wikipedia]
The chart example "Normal (Gaussian) distribution graph" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Marketing Diagrams solution from the Marketing area of ConceptDraw Solution Park.