Packing of Particles in Solids-space Lattices

Feb 2009
I'm soo confused, my chem book doesn't explain anything properly. All it says is Assuming a mass of 1 unit per sphere, calculate the density in units/cm3. Okay well, how am I supposed to know the mass of the oranges or whatever spheres I'm using for my experiment? Therefore, how am I supposed to figure out the density? Also, it doesn't say if I'm supposed to measure the volume of the oranges themselves, or the box around the orange? Like help me please my book is useless!