Question

Difficulty: Very hardShort-Run Cost Concepts and Calculations

A firm operating in the short run faces a total cost function given by TC=240+15Q+3Q2TC = 240 + 15Q + 3Q^2, where TCTC represents total cost in Naira (\text{₦}) and QQ represents the quantity of output produced in units. What is the firm's Average Total Cost (ATC\text{ATC}) at the output level where its Average Variable Cost (AVC\text{AVC}) is equal to 33\text{₦}33?

  1. 73\text{₦}73Answer
  2. B
    33\text{₦}33
  3. C
    273\text{₦}273
  4. D
    238\text{₦}238

Answer

The firm's Average Total Cost at the specified output level is 73\text{₦}73.
The correct answer is derived by first expressing Average Variable Cost as AVC=15+3QAVC = 15 + 3Q. Setting AVC=33AVC = 33 reveals that the firm produces 66 units of output. At this production level, Average Fixed Cost is AFC=240/6=40AFC = \text{₦}240 / 6 = \text{₦}40. Adding AFCAFC (40\text{₦}40) to AVCAVC (33\text{₦}33) yields an Average Total Cost (ATCATC) of 73\text{₦}73.

Step-by-Step Solution

1
Extract Total Fixed Cost (TFCTFC) and Total Variable Cost (TVCTVC) from the given total cost function TC=240+15Q+3Q2TC = 240 + 15Q + 3Q^2.
TFC=240TFC = 240 and TVC=15Q+3Q2TVC = 15Q + 3Q^2.
In short-run cost functions, fixed costs do not vary with output (constant term), while variable costs depend on quantity QQ.
2
Derive the Average Variable Cost (AVCAVC) equation by dividing TVCTVC by output QQ.
AVC=15Q+3Q2Q=15+3QAVC = \frac{15Q + 3Q^2}{Q} = 15 + 3Q.
Average Variable Cost measures variable cost per unit of output produced.
3
Determine the output level QQ when AVC=33AVC = \text{₦}33.
15+3Q=33    3Q=18    Q=6 units15 + 3Q = 33 \implies 3Q = 18 \implies Q = 6\text{ units}.
Solving the equation identifies the target output level.
4
Calculate Average Fixed Cost (AFCAFC) at Q=6 unitsQ = 6\text{ units}.
AFC=TFCQ=2406=40AFC = \frac{TFC}{Q} = \frac{240}{6} = \text{₦}40.
Average Fixed Cost is total fixed cost divided by quantity.
5
Compute Average Total Cost (ATCATC) at Q=6 unitsQ = 6\text{ units}.
ATC=AFC+AVC=40+33=73ATC = AFC + AVC = 40 + 33 = \text{₦}73.
Average Total Cost is the sum of Average Fixed Cost and Average Variable Cost.

Key Concept

Short-Run Cost Function Derivation and Average Cost Relationships
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