The gross national income (GNI) of a certain country (in billions of U.S. dollars) can be approximated by f(t) = 1046 e .134, where t= 0 corresponds to the year 2000 (a) Find f'(t) (b) At what rate was the GNI changing in 2000? (c) Repeat part (b) for 2009 (a) f'(t) = (b) In 2000, the GNI was changing at a rate of about $ billion per year. (Round to the nearest integer as needed.) (c) In 2009, the GNI was changing at a rate of about $ billion per year. (Round to the nearest integer as needed.)