Gravitation

Consider a planet whose density is same as that of the earth but whose radius is three times the radius '\(R\)' of the earth. The acceleration due to gravity '\(\mathrm{g}_{\mathrm{n}}\)' on the surface of planet is \(\mathrm{g}_{\mathrm{n}}=\mathrm{x}\). \(\mathrm{g}\) where \(\mathrm{g}\) is acceleration due to gravity on surface of earth. The value of '\(\mathrm{x}\)' is