The number of oil changes conducted by a service station depends on the number of workers as follows: Assume that all inputs (service bins, telephone, and utilities) other than labor are fixed in the short run.

b. Over what range of labor input are there increasing returns to labor? diminishing returns to labor? negative returns to labor?

c. Over what range of labor input is marginal product greater than average product? What is happening to average product as employment increases over this range?

d. Over what range of labor input is marginal product smaller than average product? What is happening to average product as employment increases over this range?