Gamma Distribution

A distribution of independent $Exponential(\lambda )$ values.

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$$f(x)=\{\begin{array}{ll}\frac{{\lambda }^a}{\Gamma (a)}{x}^{a-1}{e}^{-\lambda x}& x>0\\ 0& x\le 0\end{array}$$

• Where $a,\lambda >0$
• Where $\Gamma$ is the Gamma Function
• Denoted by $X\sim Gamma(a,\lambda )$