A cell site is a site where electronic communications equipment is placed in a cellular network for the use of mobile phones. The numbers y of cell sites from 1985 through 2014 can be modeled by
y = 320,110/1 + 374e-0.252t
where t represents the year, with t = 5 corresponding to 1985.
(a) Use the model to find the numbers of cell sites in the years 1998, 2003, and 2006.
(b) Use a graphing utility to graph the function.
(c) Use the graph to determine the year in which the number of cell sites reached 270,000.
(d) Confirm your answer to part (c) algebraically.