The solidification time follows Chvorinov's rule, which is given by:
\[
T = \frac{C \cdot V^2}{A}
\]
The ratio of the solidification times for the cube and cylinder is:
\[
\frac{T_{{cube}}}{T_{{cylinder}}} = \frac{s^6 / 6s^2}{4\pi r^2 / r^6}
\]
Since the volumes of the cube and the cylinder are the same:
\[
s^3 = \pi r^3
\]
Thus, the relationship between \( s \) and \( r \) is:
\[
s = \left( \pi r^3 \right)^{1/3}
\]
Substituting this into the ratio, we find:
\[
\frac{T_{{cube}}}{T_{{cylinder}}} = 0.83
\]