how to calculate E(1/x) and E(1/X^2)when given E(X)=3

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- December 9th 2009, 12:28 AMrajrhow to calculate E(1/x)
how to calculate E(1/x) and E(1/X^2)when given E(X)=3

- December 9th 2009, 12:30 AMrajr
Am i right in saying e(1/x)=1/e(x)=1/3 thank you

- December 9th 2009, 02:20 AMMoo
No, that's false ;)

And without any further information, it's not possible to calculate E[1/X] - December 9th 2009, 02:23 AMrajr
Sorry I should have explained the question in detail

X~Gamma(a,3)

i.e. am i right in saying the inverse of the distribution is 1/X~Gamma(a,1/3).

Therefore E(1/X)=1/3a and Var(1/X)=1/3(a^2)

Thanks for your response - December 9th 2009, 02:31 AMMoo
- December 9th 2009, 03:42 AMmr fantastic
Does it agree with what is here: Inverse-gamma distribution - Wikipedia, the free encyclopedia