Final answer:
To maximize profits in a perfectly competitive market, your family should equate marginal revenue with marginal cost. Without specific cost data, exact profit-maximizing quantity cannot be determined, but adjustments should be made based on marginal costs in relation to market price.
Step-by-step explanation:
To determine if your family should keep selling 17 car washes per day to maximize profit in a perfectly competitive market, we need to apply the golden rule of profit maximization. This rule states that to maximize profit, a firm should produce at the quantity where marginal revenue (MR) equals marginal cost (MC).
Since it is given that customers are only looking for the cheapest price, we can assume the price is equal to marginal revenue. Without specific cost information for the car wash, we cannot calculate the exact profit-maximizing quantity. However, if the marginal cost of washing an additional car is less than the price, it would make sense to wash more cars. Conversely, if the marginal cost of additional car washes exceeds the market price, washing less would be the profit-maximizing choice.
You must also consider fixed costs in your calculation of total costs. Even though fixed costs do not change with the quantity produced, they still affect the average total cost (ATC). If the price covers the ATC, then your family's business is making a profit. To maximize profit, you should continue to adjust the number of car washes provided until MC just equals MR.