Calculating Molecule Density at High Altitudes

[btbam91]

At an altitude of 100 km, the average distance between air molecules is approximately 3x10^-4 mm. Compute the number of molecules contained in a spherical volume of diameter 1 um(micrometer)

I know this is probably a stupid question, but do I just find the volume of the sphere using the 1 micrometer and divide that quantity by the average distance cubed?

 

[Borek]

That would be my approach.

Please don't ignore the template.