Final answer:
With an increase in market price to $6, the firm's profit-maximizing output level would typically increase since the additional revenue would outweigh the marginal costs up to a new, higher equilibrium point.
Step-by-step explanation:
The profit-maximizing output level is determined by where marginal revenue (MR) equals marginal costs (MC). According to the information, the maximum profit occurs between 70 and 80 units of output, but the MR=MC rule applies strictly at 80 units. If the market price increases to $6, it implies that the firm's revenue for each additional unit sold increases, which may shift the MR curve upward. The new equilibrium where MR=MC would also likely shift to the right, suggesting the firm would increase its output beyond 80 units to maximize profits at the new higher market price. However, without more data from Table 8.14, we can't determine the exact new output level. It's important to remember that firms always aim to produce at the level where profits are maximized, which is the point where the difference between total revenue and total costs is the greatest. If the market price rises, it typically creates an incentive for the firm to increase production as long as the additional revenue from selling more units (MR) exceeds the additional cost of producing those units (MC).