The Student Room Group

statistics means, probability distributions

prove that

<v4><v2>2<v^4> \geq <v^2>^2

for any probability distribution f(v)

this is what ive attempted so far

WIN_20151208_164220.JPG

dont think that even makes sense
Original post by swagadon
prove that

<v4><v2>2<v^4> \geq <v^2>^2

for any probability distribution f(v)

this is what ive attempted so far

WIN_20151208_164220.JPG

dont think that even makes sense


I'm not familiar with the chevron notation, but judging by your attempt this is just the expectation - perhaps on a more sophisticated level?

So, you want to show E(X4)E2(X2)E(X^4)\geq E^2(X^2)

Rearranging we have
E(X4)E2(X2)0E(X^4)- E^2(X^2)\geq 0

Which looks like the variance of X2X^2

Spoiler

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