The sales S (In billions of dollars) for Starbucks from 2009 through 2014 can be modeled by the exponential function s(t) = 3.71(1.112) where t is the time in years, with t = 9 corresponding to 2009.+ (Round your answers to two decimal places.) (a) Use the model to estimate the sales in 2019 in billions of dollars. $ billion (b) Use the model to estimate the sales in 2020 in billions of dollars. $ billion