Computing standard deviation of parameter

Question

Given that I have a parameter $$\chi =\frac{\langle M^2\rangle}{TL^2},$$ how would I compute the standard deviation of $\chi$? I suspect it should be, $$\sqrt{\frac{\langle M^4\rangle-\langle{M^2}\rangle}{TL^2}}$$ based on my limited knowledge of statistics, but I'm not too sure. Similarly, suppose, $$C=\frac{\langle E^2\rangle-\langle E\rangle^2}{T^2L^2},$$ how would I compute the standard deviation of this quantity?

Answer 1

The standard deviation of $C$ is $\sqrt{E(C^2)-(E(C))^2}$, where $E$ means expectation (average). It is not clear what parameters defining $C$ are random variables.