The rate of change in sales for a technology company from 2008 through 2013 can be modeled by dS/dt = 0.0975t^2 + 2.176t 11.73; where S is the sales (in billions of dollars) and t is the time in years, with t = 8 corresponding to 2008. In 2009, the sales for this company were $2.5 billion. (a)Find the model for the sales of this company. S =

b)What were the average sales (in billions of dollars) of this company from 2008 through 2013? (Round your answer to three decimal places.)