3. In New Zealand, suppose the relationship between a cow's total output of milk and the amount of grain it is fed as follows: Amount of grain (in kgs) Amount of milk (in litres) 1,200 5,917 1,800 7.250 2,400 8.379 3,000 9.371 a. Calculate the average product of grain when each kilogram is used. Average product b. Estimate the marginal product of grain Marginal product c. Does this production function exhibit diminishing marginal returns