Final answer:
In a perfectly competitive market, the price of a good remains constant regardless of the quantity produced. Therefore, the formula for calculating marginal revenue product is Δ in Total Revenue/Δ in Resource Quantity.
Step-by-step explanation:
A perfectly competitive market is a market structure where each firm faces many competitors that sell identical products and is considered a price taker. In such a market, the price of a good or service is determined through the interaction of supply and demand and remains constant regardless of the quantity produced. Therefore, the formula that accounts for how the price of the good changes when more resources are used to produce it is Marginal Revenue Product = Δ in Total Revenue/Δ in Resource Quantity.