The price-demand equation and cost function for the production of vacuums are given as follows:

p(x) = 250 - 0.005x and C(x) = 100,000 + 20x

where x is the number of vacuums that can be sold at $p per vacuum and C(x) is the total cost (in dollars) of producing x vacuums. (12 points)

1. Find the profit function.
2. Find the equation for the marginal profit.
3. Find the marginal profit when x = 1500 and interpret this quantity.