Many commercial cubic ferrites can be prepared in a combination of both normal and inverse spinel structures. Calculate the magnetic moment of a unit cell of manganese ferrite $(MnF{e}_2{O}_4)$ if it occurs in $($a$)$ an inverse spinel, $($b$)$ a normal spinel, or $($c$)$ a $50$:$50$ mixture of inverse and normal spinel structures. $($Look up how magnetic moments are aligned in spinel and inverse spinel structure from your book or other sources$).$