Physics problem! Gravitation again.?

Density = m/Vol. since the radius is given, the vol can be directly calculated using V = 4/3*pi*r^3 = 4/3*pi*(1570 x 10^3)^3 = 1.62 x 10^19 m^3. Now for the M. Use Newton's Law of Gravitation GMm/r^2 = mg so g = GM/r^2 Solve for M = g*r^2/G = 1.33m/s^2*(1570x10^3)^26.73x10^-11 = 4.87 x 10^22 kg So density = 4.87x10^22kg/1.62x10^19m^3 = 3.00x10^3kg/m^3