Consider a system of N (>>1) particles with mass m in a (big) volume V. What is the average energy per particle if the particles are fermions. I did some calculations and I came up with <E> = (2/3)*Fermi-energy. Is this correct? I could post my calculations but my Latech-skills are very poor and the calculation involves some long integrals. I used <E> = Etotal / N and calculated N and E by using the Fermi-Dirac distribution. The other question is the same but then for bosons. In that case the average energie would be 0 right?