Students in a fifth-grade class were given an exam. During the next 2 years, the same students were retested several times. The average score was given by the model f(t)=89−17log10(t+1),0≤t≤24 where t is the time in months.
(a) What is the average score on the original exam? (b) What was the average score after one year? (c) After how many months would it take for it to predict that the average dropped to 82? (Assume that the the model could continue past two years, if necessary)