Standard Enterprises produces an output that it sells in a highly competitive market at a price of $100 per unit. Its inputs include two machines (which cost the firm $50 each) and workers, who can be hired on an as-needed basis in a labor market at a cost of $2,800 per worker. Based on the following production data, how many workers should the firm employ to maximize its profits?

Machines Workers Output 2 O 0 2 1 60 2 2 100 2 129 2 4 148 5 160 2 168