1. The problem statement, all variables and given/known data Given the wave function psi(x,0) = 3/5 sqrt(2/L) sin(xpi/L) + 4/5 sqrt(2/L) sin(5xpi/L) in an infinite potential well from 0 to L, what is the expectation value <x> and rms spread delta E = sqrt(<E^2>-<E>^2) 2. Relevant equations <x> = integral from 0 to L of psi*xpsi dx 3. The attempt at a solution I know that the expectation value <E> is just 3/5 E1 + 4/5 E2, however I'm not sure how to find the rms spread of it without cumbersome algebra. And the same with <x>.