The sales S (in thousands of units) of a new CD burner after it has been on the market for t years are modeled by S(t) = 110{1 e'\"]. Thirteen thousand units of the new product sold the first year. (a) Complete the model by solving for k. (Round your answer to four decimal places.) k= (b) Sketch the graph of the model. s s 120 120 100 100 80 80 60 60 40 40 20 20 t t O 3 10 15 20 25 30 o 3 10 13 20 25 30 s s 120 120 100 100 80 80 60 60 40 40 20 20 t t O 5 10 15 20 25 30 5 10 15 20 25 30 () Use the model to estimate the number of units sold after 7 years. (Round your answer to three decimal places.) thousand units