Solve the Problem Using a Graphing Utility, Fit a Logarithmic Function Y

Multiple Choice

Solve the problem.
-In a Psychology class, the 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 average scores after t months are given in the table. $$\begin{array} { l | c c c c c } \text { Time, t ( in months) } & 1 & 2 & 3 & 4 & 5 \\\hline \text { Score, y ( in percentage) } & 86.2 & 85.7 & 85.4 & 85.2 & 85.0\end{array}$$ Using a graphing utility, fit a logarithmic function y $$y = a + b \ln x$$ the data. Using the function you found, estimate
How long will it take for the test scores to fall below 84%. Express your answer to the nearest month.

A) 8 months
B) 12 months
C) 20 months
D) 10 months