An often forgotten formula for the mean of a random variable X is given by:

\displaystyle \mu=E(X)=\sum_{x=0}^{\infty} \Big(1-F(x)\Big)

And for the continous case:

\displaystyle \mu=E(X)=\int_{x=0}^{\infty} \Big(1-F(x)\Big)

This blog post is going to illustrate how these formulas arise.

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