Volume of the sphere is:

$\overline{){\mathbf{V}}{\mathbf{=}}\frac{\mathbf{4}}{\mathbf{3}}{\mathbf{\pi}}{{\mathbf{r}}}^{{\mathbf{3}}}}$

Density is given by:

$\overline{){\mathbf{\rho}}{\mathbf{=}}\frac{\mathbf{m}}{\mathbf{V}}}$

Air enclosed in a sphere has density 1.5 kg/m^3. What will the density be if the radius of the sphere is halved, compressing the air within?