Answer
$k=2130N/m$
Work Step by Step
In the explanation, it can be concluded that the two forces present equal out. These are the spring force ($kx$) and the weight ($mg$). This means that $$mg=k\Delta x$$ Solving for $k$ yields $$k=\frac{mg}{\Delta x}$$ Substituting known values of $m=9.09kg$, $\Delta x=4.18cm=0.0418m$, and $g=9.80m/s^2$ yields a spring constant of $$k=\frac{(9.09kg)(9.80m/s^2)}{0.0418m}=2130N/m$$
