The total profit (in dollars) from the sale of x gas grills is
P(x) = 20x - 0.02x2 - 320 0 ≤ x ≤ 1,000
(A) Find the average profit per grill if 40 grills are produced.
(B) Find the marginal average profit at a production level of 40 grills and interpret the results.
(C) Use the results from parts (A) and (B) to estimate the average profit per grill if 41 grills are produced.