Question

find the moment of inertia about an axis perpendicular to the disc and passing through its centre

Answer 1

MI of disc about an axis through its axis = MR2/4

Now, MI of the same disc about an axis passing through a point on rim and perpendicular to the plane
= (MR 2/2) + MR2       (Parallel axis theorem)
= 3/2 *(MR2)