Are there fixed costs in the long-run? Explain briefly. What are diminishing marginal returns as they relate to costs? Which costs are measured on per-unit basis: fixed costs, average cost, average variable cost, variable costs, and marginal cost? What is a production technology? In choosing a production technology, how will firms react if one input becomes relatively more expensive? What is a long-run average cost curve? What is the difference between economies of scale, constant returns to scale, and diseconomies of scale? What shape of a long-run average cost curve illustrates economies of scale, constant returns to scale, and diseconomies of scale? What are the four basic assumptions of perfect competition? Explain in words what they imply for a perfectly competitive firm. What is a "price taker" firm? How does a perfectly competitive firm decide what price to charge