4.) The table gives the cumulative sales of iPods since their introduction.Cumulative iPod Sales

Year	Sales (million iPods)
2003	0.62
2004	5.636
2005	29.933
2006	69.542
2007	121.172
2008	175.5

(a) Find the function for the quadratic model that gives sales in million iPods, where x is the number of years after 2003, with data from

0 x 5.

(Round all numerical values to three decimal places.)

s(x) =

million iPods (b) Write the derivative for the sales model. (Round all numerical values to three decimal places.)

s'(x) =

million iPods per year (c) Calculate the rate of change of cumulative sales in 2007. (Round your answer to three decimal places.) million iPods per year Interpret the rate of change of cumulative sales in 2007. (Round your answer to three decimal places.)In 2007, cumulative iPod sales were ---Select--- increasing decreasing by million per year.