A certain country's factory sales of electronic goods to dealers from 1990 through 2001 can be modeled as s(t) = 0.03873 - 0.495t2 + 5.695t + 43.1 where output is measured in billion dollars and t is the number of years since 1990. (a) Calculate the average annual value of the country's factory sales of electronic goods to dealers from 1990 through 2001. (Round your answer to three decimal places.) billion dollars (b) Calculate the average rate of change of the country's factory sales of electronic goods to dealers from 1990 through 2001. (Round your answer to three decimal places.) billion dollars per year