http://www.ck12.org Chapter 4. Probability Distributions
In this first concept on probability distributions, you are going to begin by learning about normal distributions. A
normal distribution curvecan be easily recognized by its shape. The first 2 diagrams above show examples of
normal distributions. What shape do they look like? Do they look like a bell to you? Compare the first 2 diagrams
above to the third diagram. A normal distribution is called abell curvebecause its shape is comparable to a bell. It
has this shape because the majority of the data is concentrated at the middle and slowly decreases symmetrically on
either side. This gives it a shape similar to a bell.
Actually, the normal distribution curve was first called a Gaussian curve after a very famous mathematician, Carl
Friedrich Gauss. He lived between 1777 and 1855 in Germany. Gauss studied many aspects of mathematics. One
of these was probability distributions, and in particular, the bell curve. It is interesting to note that Gauss also spoke
about global warming and postulated the eventual finding of Ceres, the planet residing between Mars and Jupiter. A