Moment of inertia — UPSC IFoS 2014 Physics PYQ

Discuss the torque-free motion of a symmetric rigid body and hence estimate the period of precession of Earth's polar axis. [Use \frac{I_3 - I_1}{I_3} = 0.33, where I_1, I_2 and I_3 are the moments of inertia about the three principal axes of the Earth]