Expectation

Sometimes we associate a numerical value with each elemental event and want to know the average or expected value.

Let $f: S \rightarrow \Re$. The expected value of f is $E[f] =
\sum_{e \in S} \Pr\{e\} f(e)$.

For example, what's the expected coin flip value from the previous experiment?

Note that this is not saying that one value is more likely than the others. It is identifying the average value we get if we repeat the experiment.


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