(Table: Variable Costs for Lawns) Use Table: Variable Costs for Lawns.During the summer,Alex runs a lawn-mowing service,and lawn-mowing is a perfectly competitive industry.Assume that costs are constant in each interval;so,for example,the marginal cost of mowing each of the lawns from 1 through 10 is $10.Also assume that he can only mow the quantities of lawn given in the table (and not numbers in between) .His only fixed cost is $1,000 for the mower.His variable costs include fuel,his time,and mower parts.If the price for mowing a lawn is $70,how much is Alex's total revenue at the profit-maximizing output?

A) $3,500
B) $2,800
C) $2,100
D) $1,800

To maximize profits, Alex should continue producing until the marginal cost equals the price, as long as the price is above the marginal cost. Since the price for mowing a lawn is $70, and the table (which is not shown) presumably indicates that the marginal cost for each lawn up to a certain point is below $70, Alex will mow as many lawns as he can until the marginal cost equals or exceeds $70. Without the specific details of the marginal cost at each quantity, we assume he mows the maximum number of lawns where the marginal cost is below $70. If the profit-maximizing output is 50 lawns (for example), at $70 each, his total revenue would be 50 lawns * $70 = $3,500. This answer assumes the reader understands the concept of profit maximization in perfectly competitive markets, where firms produce up to the point where price equals marginal cost.