Food bank usage in Britain has grown dramatically over the past decade. The number of users, in thousands, of the largest food bank in year t is estimated to be N(t) = 1.3e^0.81t , where t is the number of years since 2006.105 

(a) What does the 1.3 represent in this context? Give units. 

(b) What is the continuous growth rate of users per year? 

(c) What is the annual percent growth rate of users per year? 

(d) Using only your answer for part (c), decide if the doubling time is more or less than 1 year.