The profit in dollars from the sale of x expensive watches is P(x) = 0.04x2 - 2x + 3x0.5 - 4200. Find the marginal profit when (a) x= 300, (b) x = 1000, (c) x = 6000, and (d) x 10,000. (a) When x = 300, the marginal profit is S (Round to the nearest integer as needed.) (b) When x= 1000, the marginal profit is S (Round to the nearest integer as needed.) (c) When x = 6000, the marginal profit is $ (Round to the nearest integer as needed.) (d) When x= 10,000, the marginal profit is $ (Round to the nearest integer as needed.)