The initial price of buzz.com stock is $10 per share. After 20 days the stock price is $20 per share and after 40 days the price is $25 per share. Assume that while the price of the stock is not zero it can be modeled by a quadratic function.

(a) Find the multipart function s(t) giving the stock price after t days. If you buy 1000 shares after 30 days, what is the cost?

(b) To maximize profit, when should you sell shares? How much will the profit be on your 1000 shares purchased in (a)?