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mkendall
August 19th, 2010, 10:39 AM
The expectation of a fair 6-sided die is 3.5 and the expectation of two 6-sided dice is 7. and 10.5 for three dice. Simple enough.

If the number of dice rolled is determined by the result of a roll on a 6-sided die -- that is, if you roll a 5, you then roll five 6-sided dice -- is the expectation 3.5^2, or 12.25?

In general, would the expectation be E(Y)*E(X) for a Y-sided die roll's number of X-sided dice?

NovaAesa
August 19th, 2010, 10:54 AM
It would be 12.25.

EDIT: assuming of course that by "expectation" you mean the normalized mean average of the possibilities.

mkendall
August 19th, 2010, 11:05 AM
EDIT: assuming of course that by "expectation" you mean the normalized mean average of the possibilities.

Isn't that the Expectation? Been awhile since I had to take Statistics and Probability to finish my degree.

NovaAesa
August 19th, 2010, 11:08 AM
You're right, I just looked on Wikipedia, and it's also know as simply "expectation". I had only heard it termed expected value and first-moment before.

mkendall
August 19th, 2010, 11:10 AM
First Moment definitely sounds familiar, but more from my Physics studies than Mathematics.

Thanks for the confirmation.