The table below shows the total product, average product and marginal product of a firm which uses labor as its main variable input and a machine as its fixed input. Quantity of labor Total product Marginal product Average product 1 2 40 90 60 70 3 4 5 9 324 7 26 8 0 9 333 10 -65 a) Complete the table. 56 56 b) At what level of variable input is the total output at its maximum level? c) At what level of variable input employed will diminishing returns start to set in? [6 marks] [2 marks]