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# S1 - Expectation of a function of X Watch

1. E[g(X)]

If I'm not mistaken, E(X) is the mean. But what's g? It's the rule, but I'm not sure what it's supposed to mean.

Will g be given as a specific number, in which case I should multiply all the values of x (0,1,2,etc.) by g, which is the same as multiplying the mean by g?

Sorry, I can't find a question on it so I can't work it out on my own...
2. I think here g(X) means a function of X - e.g. 4X + 2
E[g(X)] means expected value of X when the function is applied
3. Ahhh right...I see. Thanks.

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Updated: December 25, 2010
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