An emerald mine is the only source of employment in a small town. Each employee can dig 2 tons of coal per hour, which sell at $10/ton.

The marginal revenue product of an emerald miner is $20/hour. Labor supply is L = 50W, where W is the wage rate

a) Find the monopsonist firm's total expenditure on labor

b) Find the monopsonist firm's marginal expenditure

c) What is the optimal number of workers per hour that the firm should hire? How many workers would be hired in a perfectly competitive market?

d) What wage will the workers earn working for the monopsonist firm? What would the workers earn in a perfectly competitive market?