Recently, general results obtained from the study of the autocorrelation functions of liquids were used for a more accurate analysis of the full small angle scattering pattern fi om mono and polydisperse systems with interparticle interaction. The effects of polidispersity and density, in close-packed systems of hard spheres (case 1) and hard spheres with permeable shell (case 2) with Schulz distribution of radii, were investigated by Mengoni [J. Chem. Phys. 87, 2560 (1987)] by a numerical integration of the intensity in the framework of the Born-Green kinetic theory for fluids. In this paper we generalize the case 1 reported by Mengoni to a system of spherical particles of radius r(i) with an interacting hard sphere potential of radius R(HSi)proportional to r(i) and analytically solve the equations for the intensity.