=+c. An increase in fixed cost increases marginal cost.

d. When marginal cost is above average total cost, average total cost must be falling. 9. Mark and Jeff operate a small company that produces souvenir footballs. Their fixed cost is $2,000 per month. They can hire workers for $1,000 per worker per month. Their monthly production function for footballs is as given in the accompanying table.

Quantity of labor (worker s) Quantity of footballs 0 to}

1 300 2 800 3 1,200 4 1,400 5 1,500