The circulation C of a certain magazine as a function of time t is given by the following formula. 5.2 0.1 + 0.3 Here Cis measured in thousands, and t is measured in years since the beginning of 2006,...

Extracted text: The circulation C of a certain magazine as a function of time t is given by the following formula. 5.2 0.1 + 0.3 Here Cis measured in thousands, and t is measured in years since the beginning of 2006, when the magazine was started. (a) Make the graph of C versus t covering the first 6 years of the magazine's existence. 60 50 50 40 40 30 30 20 20 10 10 1 2 3 5 6. 1 2 3 4 6 60 60 50 50 40 40 30 30 20 20 10F 10 2 3 4 5 6 2 3 4 5 6 (b) Express using functional notation the circulation of the magazine 18 months after it was started. Find that value. (Round your answer to two decimal places.) thousand magazines (c) Over what time interval is the graph of C concave up? The graph of C is concave up from t = (smaller value) to t= (larger value) years. Explain what "concave up" means in practical terms. O The circulation was increasing more and more quickly. The circulation was decreasing more and more quickly. O The circulation was decreasing more and more slowly. O The circulation was increasing more and more slowly. (d) At what time was the circulation increasing the fastest? (Round your answer to the nearest year.) years (e) Determine the limiting value for C. C = |thousand magazines Explain your answer in practical terms. O Itis the initial circulation. O Itis the level of market saturation. O It is the circulation with the highest growth rate. O It is the circulation att = 1.5.