A firm has a weekly short-run production function of

Q = 400L - 10L²

It can sell all the output it can produce at a price of $40 per unit (P = $40). It can hire all the workers it wants for $800 per week.

1. If the firm currently has 10 workers and adds one more, find how much that 11^th worker adds to physical output ( Q).
2. How much is the additional output found in part a. worth?
3. The MPL for this production function is MPL = 400 -20L. Find the profit-maximizing number of workers.
4. If the price the firm gets for its output falls to $30, how many workers will they now want to hire? (Remember, fractional workers = part-time, so that is possible)