The following graph shows the approximate value of the United States Consumer Price Index (CPI) from December 2006 through July 2007. n H C P] Dec 2006Ju|}' 2007 209 208 207 206 205 204 203 202 201 > f 0 l ' 7 09006 JulyuO? u ,4 4. an 0 The approximating curve shown on the figure is given by m) = 0.04t3 + 0.4t2 + 0.1: + 202 (0 s r s 7), where t is time in months since the start of December 2006. l (a) Use the model to estimate the monthly inflation rate in May 2007 (t = 5). Recall that the inflation rate is I (t). (Round your answer to three decimal places.) I(t) :l x