Answer
A factor of 2
Work Step by Step
We know that
$I_i\omega_i=I_f\omega_f$
This can be rearranged as:
$\frac{\omega_f}{\omega_i}=\frac{I_i}{I_f}$
$\implies \frac{\omega_f}{\omega_i}=\frac{I_i}{\frac{1}{2}I_i}$
$\implies \frac{\omega_f}{\omega_i}=2$
