Answer
$f=1.91Hz$
Work Step by Step
We know that
$f=\frac{\omega}{2\pi}$
but $v_{max}=A\omega$ where $A$ represents amplitude and $\omega$ is the angular velocity
now $\omega=\frac{v_{max}}{A}=\frac{1.20}{0.1}=12\frac{rad}{s}$
Put the value of $\omega$ and $\pi$ in the very first equation, we get
$f=\frac{12}{6.28}$
$f=1.91Hz$
