Students in a zoology class took a final exam. They took equivalent forms of the exam at monthly intervals thereafter. After t months, the average score S(t), as a percentage, was found to be given by the following equation, where t0. Complete parts (a) through (e) below. S(t)=81-15 In (t+1), Osts 80 a) What was the average score when they initially took the test? The average score was %. (Round to one decimal place as needed.) b) What was the average score after 4 months? The average score after 4 months was %. (Round to one decimal place as needed.) c) What was the average score after 24 months? The average score after 24 months was %. (Round to one decimal place as needed.) d) Find S'(t). S'(t)= e) Find S'(4) and S'(24), and interpret the meaning of these numbers. S'(4)=which means that after 4 months, the average score is (Type integers or decimals.) by points a month and S'(24)=.which means that after 24 months, the average score is by points a month.