NO CALCULATOR IS ALLOWED FOR THIS QUESTION. Show all of your work, even though the question may not explicitly remind you to do so. Clearly label any functions, graphs, tables, or other objects that you use. Justifications require that you give mathematical reasons, and that you verify the needed conditions under which relevant theorems, properties, definitions, or tests are applied. Your work will be scored on the correctness and completeness of your methods as well as your answers. Answers without supporting work will usually not receive credit. Unless otherwise specified, answers (numeric or algebraic) need not be simplified. If your answer is given as a decimal approximation, it should be correct to three places after the decimal point. Unless otherwise specified, the domain of a function f is assumed to be the set of all real numbers ac for which f (a) is a real number. 41 20 for 0 20 t2 +600 The total accumulated revenue a company has received up to time t is modeled by the function R defined above, where R (t) is measured in millions of United States dollars and t is the time in years since 1980. (a) Find lim R (t). Explain the meaning of lim R (t) in the context of the problem. t- + 0o 1-+ 00(b) Is the function R continuous at t = 20 ? Justify your answer. 0 / 10000 Word Limit BI U X X2 0 / 10000 Word Limit (c) The company's total accumulated expenses up to time t is modeled by the function E defined by E (t) = 3log2 (12t + 4), where E (t) is measured in millions of United States dollars and t is the time in years since 1980. According to these models, is there a time t, for 0