Total, average and marginal productTotal product (TP] is the total output that a firm produces, using its fixed and variable factors in a given time period. As we have already said, output in the short run can only be increased by applying more units ol the variable factors to the lixed factors.

Average product (AP) is the output that is produced, on average, by each unit of the variable factor. AP = ^, where TP is the total output produced and V is the number of units ol the variable factor employed. Marginal product (MP) is the extra output that is produced by using an extra unit of the variable factor. MP = 4B, where ATP is the change in total output and AV is the change in the number of units of the variable factor employed.

Take an example. A firm has four machines (fixed factors) and increases its output by using more operators to work the machines. Production figures for each week are given in Table 6.1.