Two small spheres of masses 10kg and 30 kg are joined by a rod of length 0.5 m and of negligible mass. The M.I of the system about a normal axis through centre of mass of the system is

When two particles of masses m1 and m2 are at a distance d apart, M.O.I. of the system about an axis passing through the COM and perpendicular to the line joining the particles is given by