A light rod of length l has two masses m₁ and m₂ attached to its two ends. The moment of inertia of the system about an axis perpendicular to the rod and passing through the centre of mass is : 

\(\frac{m_1 m_2}{m_1 + m_2} l^2\)

\(x_1 = \frac{m_2l}{m_1+m_2} ; x_2 = \frac{m_1l}{m_1+m_2}\)

I = \(m_1x_1^2 + m_2 x_2^2\)

  = \(\frac{m_1 m_2}{m_1 + m_2} l^2\)