11. The concept of opportunity cost is useful for manager in decision making.
13. Sunk costs are those costs which are incurred in the past or that have to be incurred in the future as result of a contractual agreement.
15. Historical cost of an asset states the cost of plant, equipment and materials at the price paid originally for them, while the replacement cost states the cost that the from would have to incur if it wants to replace or acquire the same assets now.
17. All the explicit costs like payment of rent, wages, salaries, interest, transport charges, etc., fall in the category of out-of-pocket costs.
19. Those costs whose postponement does not affect (at least for some time) the operational efficiency of the firm, are: known as postponable costs, e.g., the maintenance of building, renovation of office etc.
21. They are associated with the existence of a firm's plant and, therefore, must be paid even if the firm's level of output is zero.