The link above will take you to a page to practice calculating the edge length of a cubic unit cell (simple, body-centered, or face-centered) from an atomic radius.
The link above will take you to a page to practice calculating the volume of a cubic unit cell (simple, body-centered, or face-centered) from an atomic radius.
The link above will take you to a page that will allow you to check your answers to PS5.4, PS5.5 and PS5.6. See if your answers are reasonable or not.