Answer
Model:$\quad S=55.49\ln t+39.67$
It is more reasonable to extrapolate to the right (positive direction).
.
Work Step by Step
Using desmos.com online calculator, we add a table with $t$ and $S$ as variable names, and enter the given values.
In the next free cell, enter
$S\sim A\ln(t)+C$
and check the "Log mode" box.
The calculator returns
$A\approx 55.49$
$C=39.67$
(see graph attached to the solution).
Model:$\quad S=55.49\ln t+39.67$
Extrapolating to the left (the negative direction), eventually leads to negative values, which is unreasonable.
It is more reasonable to extrapolate to the right (positive direction).
