A concentration ratio a. measures the percentage of total output supplied by the four largest firms in the industry. b. reflects the level of competition in an industry. c. is related to the control that each firm has over price. d. All of the above are correct.

Mr. smith recently faced a choice between being (a) an economics profes-sor, which pays $60,000/yr, or (b) a safari leader, which pays $50,000/yr. after careful deliberation, smith took the safari job, but it was a close call. "for a dollar more," he said, "i'd have gone the other way."now smith's brother-in-law approaches him with a business proposition. the terms are as follows: - smith must resign his safari job to work full-time in his brother-in-law's business.- smith must give his brother-in-law an interest-free loan of $100,000, which will be repaid in full if and when smith leaves the business. (smith currently has much more than $100,000 in the the business will pay smith a salary of $70,000/yr. he will receive no other payment from the business. the interest rate is 10 percent per year. apart from salary considerations, smith feels that working in the business would be just as enjoyable as being an economics professor. for simplicity, assume there is no uncertainty regarding either smith's salary in the proposed business or the security of his monetary investment in it. should smith join his brother-in-law and, if so, how small would smith's salary from the business have to be to make it not worthwhile for him to join? if not, how large would smith's salary from the business have to be to make it worthwhile for him to join?

When interest is compounded continuously, the amount of money increases at a rate proportional to the amount s present at time t, that is, ds/dt = rs, where r is the annual rate of interest. (a) find the amount of money accrued at the end of 3 years when $4000 is deposited in a savings account drawing 5 3 4 % annual interest compounded continuously. (round your answer to the nearest cent.) $ (b) in how many years will the initial sum deposited have doubled? (round your answer to the nearest year.) years (c) use a calculator to compare the amount obtained in part (a) with the amount s = 4000 1 + 1 4 (0.0575) 3(4) that is accrued when interest is compounded quarterly. (round your answer to the nearest cent.) s = $

Classify each of the following items as a public good, a private good, a natural monopoly good, or a common resource.(a) measles vaccinations (b) tuna in the pacific ocean (c) airline service in the united states (d) local storm-water system