The number of research articles in a prominent journal written by researchers during 1983–2003 can be approximated by U(t) = 4.1e0.6t 0.2 + e0.6t thousand articles per year (0 ≤ t ≤ 20) where t is time in years (t = 0 represents 1983). (a) Find an (approximate) expression for the total number of articles (in thousands) written since 1983 (t = 0). HINT [See Example 5.] (Round your coefficients to two decimal places.) N(t) = (b) Roughly how many articles were written from 1983 to 2003? (Round your answer to the nearest whole number.) thousand articles