Final answer:
Marginal revenue is calculated by differentiating the total revenue function and evaluating it at the given quantity of items sold. In this case, the derivative of the total revenue function concerning the quantity sold would be evaluated at 13 items to find the marginal revenue.
Step-by-step explanation:
The student has asked to find the marginal revenue when 13 items are sold, given the demand function d(x) = √(-0.25x² + 6x + 110) dollars, where x is the number of units sold. To determine the marginal revenue, we need to first acquire the total revenue, which is the product of price and quantity at each point on the demand curve. From the demand function, we can derive the total revenue function, and then find the derivative of the total revenue function to obtain the marginal revenue function.
Marginal revenue can be calculated as the change in total revenue divided by the change in quantity. After obtaining the marginal revenue function, we can substitute x = 13 into the marginal revenue function to find the marginal revenue for 13 sold items. This approach utilizes calculus, particularly differentiation, to determine the rate of change of revenue concerning the number of items sold.