If we assume shape of earth be solid spherical.Then, the volume of earth\\\\(=4/3\\pi R^3\\\\)where R is radius of earth.Given, volume of earth\\\\(=V=4/3\\pi R^3\\\\)surface area of earth\\\\(=A=4\\pi R^2\\\\)So, \\\\(V/A=(4/3R^3)/4\\pi R^2\\\\)or \\\\(V/A=R/3\\\\)or, \\\\(R=3V/A\\\\)Now, capacitance of earth\\\\(=4\\pi \\in_0R\\\\)\\\\(=4\\pi \\in_0\\dfrac{3V}{A}\\\\)\\\\(=\\dfrac{12\\pi\\in_0V}{A}\\\\).