As we have seen, the cost of producing 300 machines rather than no machines is 90 units of food. But it isn't really a question of producing 300 machines or nothing. Economia has to choose among all of the possible outputs of machines. We define marginal cost as the cost of producing one more machine.
Marginal cost is always the concept of cost most important for the allocation of resources.
Marginal cost will vary as the output of machines varies. However, Table 1 does not give us quite enough information to compute the marginal costs for the different outputs of machines. For example, we can see from Table 1 that , if Economia increases its production of machines from 300 to 400, it will have to cut back on food from 910 units to 840 units, a difference of 70 units of food.