Simple Harmonic Motion

A light spring is suspended with mass '$m_1$' at its lower end and its upper end is fixed to a rigid support. The mass is pulled down a short distance and then released. The period of oscillation is T second. When a mass '$m_2$' is added to '$m_1$' and the system is made to oscillate the period is found to be $\dfrac{3}{2}$ T. The ratio $\left(\dfrac{m_1}{m_2}\right)$ is