Statistics & Probability
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Normal Distribution

Probability density of the bell curve.

Formula

f(x)=1σ2πe−(x−μ)22σ2f(x) = \frac{1}{\sigma\sqrt{2\pi}}e^{-\frac{(x-\mu)^2}{2\sigma^2}}

Variables

\muMean
\sigmaStandard deviation

Example

About 68% of a normal distribution lies within one σ of the mean, 95% within two.

Did You Know?

The bell curve is so universal that Francis Galton called it a "wild form of cosmic order".

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