Question

Difficulty: HardShort-Run Cost Concepts and Calculations

A commercial printing enterprise operating in the short run produces 55 thousand brochures at an Average Fixed Cost (AFC\text{AFC}) of 160\text{₦}160 per thousand and an Average Variable Cost (AVC\text{AVC}) of 120\text{₦}120 per thousand. When the firm expands output to 1010 thousand brochures, its Total Cost (TC\text{TC}) rises to 2,650\text{₦}2,650. What is the Marginal Cost (MC\text{MC}) per thousand brochures over this range of output?

Answer: 250

Answer

The Marginal Cost (MC\text{MC}) per thousand brochures over this output range is 250\text{₦}250.
To find the Marginal Cost (MC\text{MC}), first compute initial Total Cost at 55 units: TC1=(AFC+AVC)×Q=(160+120)×5=1,400\text{TC}_1 = (\text{AFC} + \text{AVC}) \times Q = (160 + 120) \times 5 = \text{₦}1,400. Next, determine the change in total cost when expanding to 1010 units: ΔTC=2,6501,400=1,250\Delta \text{TC} = \text{₦}2,650 - \text{₦}1,400 = \text{₦}1,250. Dividing this by the change in output (ΔQ=105=5\Delta Q = 10 - 5 = 5) gives MC=1,2505=250\text{MC} = \frac{1,250}{5} = \text{₦}250.

Step-by-Step Solution

1
Calculate Total Cost at initial output level (Q1=5Q_1 = 5)
ATC1=AFC1+AVC1=160+120=280\text{ATC}_1 = \text{AFC}_1 + \text{AVC}_1 = 160 + 120 = \text{₦}280 per thousand. Therefore, TC1=ATC1×Q1=280×5=1,400\text{TC}_1 = \text{ATC}_1 \times Q_1 = 280 \times 5 = \text{₦}1,400.
Total cost at an output level is equal to Average Total Cost multiplied by the output quantity.
2
Determine the change in Total Cost (ΔTC\Delta \text{TC}) and change in Quantity (ΔQ\Delta Q)
ΔTC=TC2TC1=2,6501,400=1,250\Delta \text{TC} = \text{TC}_2 - \text{TC}_1 = 2,650 - 1,400 = \text{₦}1,250; ΔQ=Q2Q1=105=5\Delta Q = Q_2 - Q_1 = 10 - 5 = 5 thousand brochures.
Marginal cost measures the change in total cost resulting from a change in the total output quantity.
3
Calculate Marginal Cost (MC\text{MC})
MC=ΔTCΔQ=1,2505=250\text{MC} = \frac{\Delta \text{TC}}{\Delta Q} = \frac{1,250}{5} = \text{₦}250 per thousand brochures.
Dividing the change in total cost by the change in output yields the unit marginal cost over the interval.

Key Concept

Short-Run Marginal Cost and Total Cost derivation from Average Cost components
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