Question: Effect of advertising on hotel revenue the total annual revenue r of the miramar resorts hotel is related to the amount of money x the hotel spends on advertising its services by the function
R(x) = -0.003x3 + 1.35x2 + 2x + 8000 (0 ≤ t ≤ 400)
Where both r and x are measured in thousands of dollars .
A. Find the interval where the graph of r is concave upward and the interval where the graph of r is concave downward. What is the inflection point of r?
B. Would it be more beneficial for the hotel to increase its advertising budget slightly when the budget is $140,000 or when it is $160,000?