A manufacturer can produce digital recorders at a cost of 5050 dollars each. It is estimated that if the recorders are sold for pp dollars apiece, consumers will buy q=120pq=120p recorders each month.

a) Express the manufacturer's profit P as a function of q. P = __________

b) What is the average rate of profit obtained as the level of production increases from q=0 to q=15?

The average rate of profit is __________ dollars per unit.

c) At what rate is profit changing when q=15 recorders are produced?

The rate at which the profit is changing is __________ dollars per unit.