Which market structure(s) include(s) many firms with differentiated products who can enter and exit the market freely?

In the figure above, if the wage rate is $6 per hour, then the

A) firms' surplus is the area d + e + f. B) workers' surplus is the area a + b + c. C) deadweight loss equals zero. D) Only answers A and C are correct. E) Answers A, B, and C are correct.

What are the different types of auctions based on how people place their bids?

What will be an ideal response?