The gravitational force acting on a particle due to a solid sphere uniform density and radius R, at a distance of 3R from the center of the sphere id  $F_1$. A spherical hole of radius $\raisebox{1ex}{$R$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$  is now made in the sphere as shown. The sphere with hole now exerts a force  $F_2$ on the same particle. Ratio of $F_1$  and $F_2$ is