rising marginal cost
marginal cost rises with the quantity of output produced
average total cost
is U shaped
is the sum of AFC & AVC
AFC
always declines as output rises
because the fixed costs is spread over a larger # of units produced
AVC
typically rises as output increases
because of diminishing marginal product
efficient scale
the quantity of output that minimizes ATC
(costs are at its lowest)
the relationship between MC & ATC
If MC is lower than ATC…
the cost of adding one more unit of output is low
the relationship between MC & ATC
If MC is higher than ATC…
The cost of adding one more unit of output is Higher