David tunes pianos in his spare time for extra income. Buyers of his service are willing to pay $135 per tuning. One particular week, David is willing to tune the first piano for $115, the second piano for $125, the third piano for $140, and the fourth piano for $175. Assume David is rational in deciding how many pianos to tune. His producer surplus is a. $-15. b. $20. c. $30. d. $75.

Rate of return douglas keel, a financial analyst for orange industries, wishes to estimate the rate of return for two similar-risk investments, x and y. douglas's research indicates that the immediate past returns will serve as reasonable estimates of future returns. a year earlier, investment x had a market value of $27 comma 000; and investment y had a market value of $46 comma 000. during the year, investment x generated cash flow of $2 comma 025 and investment y generated cash flow of $ 6 comma 770. the current market values of investments x and y are $28 comma 582 and $46 comma 000, respectively. a. calculate the expected rate of return on investments x and y using the most recent year's data. b. assuming that the two investments are equally risky, which one should douglas recommend? why?