Students in a computer science class took a final exam and then took equivalent forms of the exam at monthly intervals thereafter. The average score S1t2, as a percent, after t months was found to be given by the function
S(t) = 78 - 15 log (t + 1), t ≥ 0.
a) What was the average score when the students initially took the test, t = 0?
b) What were the average score after 4 months after 24 months?
c) Graph the function.
d) After what time t was the average score 50%?