In an art class, students were tested at the end of the course on a final
exam. Then they were retested with an equivalent test at subsequent time
intervals. Their scores after time \(t\), in months, are given in the following
table.
$$
\begin{array}{|c|c|}
\hline \text { Time, } t \text { (in months) } & \text { Score, } y \\
\hline 1 & 84.9 \% \\
2 & 84.6 \% \\
3 & 84.4 \% \\
4 & 84.2 \% \\
5 & 84.1 \% \\
6 & 83.9 \% \\
\hline
\end{array}
$$
a) Use the REGRESSION feature on a grapher to fit a logarithmic function
\(y=a+b \ln x\) to the data.
b) Use the function to predict test scores after \(8 \mathrm{mo} ; 10
\mathrm{mo} ; 24 \mathrm{mo} ; 36 \mathrm{mo}\)
c) After how long will the test scores fall below \(82 \% ?\)
d) Find the rate of change of the scores and interpret its meaning.