A firm's profit-maximizing condition is that marginal revenue (MR) equals marginal cost (MC). The following steps attempt to derive the relationship between the firm's price markup and the price elasticity of demand (ε) from this condition. Analyze the derivation and identify the step that contains a fundamental error.

Background Information:

• Price is denoted by P, quantity by Q, and marginal cost by MC.
• The price elasticity of demand is defined as ε = -(P/Q) * (dQ/dP).

Derivation:

A firm with market power maximizes its profit by choosing a price and quantity. The following steps show the derivation of the relationship between the firm's optimal price markup and the price elasticity of demand. Arrange these steps in the correct logical order.

Verifying the Markup-Elasticity Relationship

Deriving the Optimal Markup Rule

A profit-maximizing firm with the ability to set its own price will always choose a price-quantity combination that falls on the inelastic portion of its demand curve (where the absolute value of the price elasticity of demand is less than 1).

Evaluating the Practicality of the Markup-Elasticity Rule

The derivation of the relationship between a firm's optimal price and demand conditions involves several key mathematical expressions. Match each mathematical expression on the left with its correct economic interpretation on the right. (P = Price, Q = Quantity, MC = Marginal Cost)

A key step in linking a firm's profit-maximizing behavior to market conditions involves manipulating the first-order condition. Starting from the equality of marginal revenue and marginal cost, which can be expressed as P + Q * (dP/dQ) = MC, we can rearrange the terms to express the price markup as a fraction of the price. The resulting equation is (P - MC) / P = ______. Fill in the blank with the correct mathematical expression in terms of P, Q, and the derivative dP/dQ.

Evaluating a Disputed Derivation

Evaluating a Pricing Strategy

Profit-Maximizing Price Markup as the Inverse of Demand Elasticity