(15 points) You are hired as a management consultant to assess the productivity of the Grape- nuts factory. After observing different amounts of labor being used during different shifts (with all other inputs held fixed), you surmise that average labor productivity during a shift depends on the amount of labor, L, and is: 50-21 - 10/L. The maximum labor amount in a shift is L = 12. (a) How much labor is required to produce 250 units in a shift? (b) How much labor can be used during a shift without the marginal product of labor falling below 9? (c) At what level of L is the marginal product of labor equal to the average product of labor