Hi. On page 23 of ch 7 they use the MGF formula. Can anyone explain exactly how they use it? I am having trouble seeing how it works. Thanks!
An MGF is essentially the solution to E(e^tX). In this case, we have X=(something), which has a known distribution, and t=-2, and we're looking for E(e^-2*(something)) So we take the formula for the MGF and substitute in the parameters of the distribution and t=-2. It's something of a mathematical hack, inasmuch as it's just luck that it happens to fit the MGF form and thus you can use the MGF result.
