# Math Help - A little help

1. ## A little help

I haven't done stats in a long time....

I have a moment generating function for a r.v X as follows:

M(t) = Exp(2(e^t -1).

Is is possible to calculate Vav(e^x)?

Any suggestion?

Tks

2. Originally Posted by vish93
I haven't done stats in a long time....

I have a moment generating function for a r.v X as follows:

M(t) = Exp(2(e^t -1).

Is is possible to calculate Vav(e^x)?

Any suggestion?

Tks
For the properties of the moment generating function see the Wikipedia page.

$Var(e^x)=E(e^{2x})-E(e^x)^2$

and:

$M(t)=E(e^{tx})$

so:

$Var(e^x)=M(2)-M(1)^2$

RonL

3. ## thanks

thaks for the helo