4. A manufacturer's marginal cost of producing r units of a certain commodity is MC(x) = 3x2 - 241 + 48 dollars per unit. The cost of producing 10 units is $5, 000. Find the cost of producing 20 units of the commodity. 5. The price p(x) at which a units of a particular commodity can be sold is p(x) = 49 - r and the total cost of producing a units is C(q) = 2x2 + 4r + 200 dollars. (a) Find the profit function P(x). (b) Find the level of production z at which profit P(r) is maximized. 6. Set up the integral that describes the area of the region bounded by the r- axis and the graph of y = -2" - 4x - 3 and find the area