Answer
The model is correct to one significant digit.
Work Step by Step
For $2020$ ($120$ years after 1900,) $t=1200$.
Inserting $t=1200$ in the model obtained in part a,
$P(120)=1.921\ln(120)-7.311\approx 1.886$
and when we compare it to $2.1$,
the two values round to the same whole,
$P(120)\approx 2,$ and $2.1\approx 2.$
The model is correct to one significant digit.
