The relationship between a worker's daily wage, w, and her daily output, q, is
q = 0.1w2 - 0.0005w3
so that the worker's marginal product with respect to her wage is
MPw = 0.2w - 0.0015w2.
What is the optimal efficiency daily wage for the firm to pay? How much output will the worker produce each day? How much profit does the firm earn on the worker's output each day if the price of output is fixed at $0.80 per unit.