How can expectation of position^2 be > L

[NucEngMajor]

How can position^2 expectation be greater than the Length of "box"? I mean <x^2> = L^2 / 3. Say L=100m then we have <x^2> = 333m. How is this possible?

 

[andrewkirk]

Why should it not be possible? After all, $100^2>100$. In any case the square is not comparable to the length, as the units of one is square metres and of the other is only metres. The volume of a cube that is 10cm per side is more than 10 $cm^3$.