Multiple Choice
Which of the following graphs best represents a typical average total cost (ATC) curve in the short run?
10. The Costs of Production
Average Total Cost: Short Run and Long Run
Multiple Choice
Why is average total cost often U-shaped?
A
At low output ATC falls as fixed costs are spread over more units, while at high output diminishing marginal returns raise variable cost per unit, causing ATC to rise.
B
Because average variable cost alone is U-shaped and average total cost exactly mirrors the shape of average variable cost.
C
Firms face rising fixed costs at first and then decreasing variable costs as output increases, creating the U-shape.
D
Technological progress lowers costs at low output but later causes costs to rise as capital becomes obsolete, producing a U-shape.
Verified step by step guidance1
Understand that Average Total Cost (ATC) is composed of Average Fixed Cost (AFC) and Average Variable Cost (AVC), so \(\text{ATC} = \text{AFC} + \text{AVC}\).
Recognize that Average Fixed Cost (AFC) decreases continuously as output increases because fixed costs are spread over more units, mathematically \(\text{AFC} = \frac{\text{Fixed Cost}}{\text{Quantity}}\).
Note that Average Variable Cost (AVC) typically decreases at first due to increasing marginal returns but eventually increases due to diminishing marginal returns, creating a U-shaped AVC curve.
Combine these effects: at low output levels, the rapid decline in AFC dominates, causing ATC to fall; at higher output levels, the rising AVC due to diminishing returns causes ATC to rise.
Conclude that the U-shape of the ATC curve results from the interplay between spreading fixed costs over more units and increasing variable costs per unit as output grows.
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