Economics 310
1. Assume the price of capital is $6 a unit and the price of labor is $10 a unit. Use the
data in the table to below to produce a new table with the following columns, output,
fixed cost, variable cost, total cost, average fixed cost, average variable cost, average total
cost and marginal cost.
Capital
2
2
2
2
2
2
2
labor
0
1
2
3
4
5
6
Total output
0
80
210
320
385
430
440
2. Use the data in question above to explain why the law of diminishing returns implies
marginal costs will be upward sloping in the short run.
3.
$
Q
Could the curve in the graph above could be a short run variable cost curve? Explain. 4. Use a graph to show the effect of each of the following on the average total cost,
average variable cost, and marginal cost. (Your should have 3 graphs, each of which with
avc, atc and mc curve)
a. increase in property tax
b. increase in wages
c. technological change
5. Is the following statement true or false and explain why? If marginal cost is increasing,
then average cost must be increasing. Answers
1.
total
output
0
80
210
320
385
430
440
Fixed var cost total cost
cost
12
0
12
12
10
22
12
20
32
12
30
42
12
40
52
12
50
62
12
60
72
afc
avc
atc
mc
xxx
0.150
0.057
0.038
0.031
0.028
0.027
xxx
0.125
0.095
0.094
0.104
0.116
0.136
xxx
0.275
0.152
0.131
0.135
0.144
0.164
xxx
0.125
0.077
0.091
0.154
0.222
1.000
2. The original data in problem shows that the marginal product decreases with the third
unit of labor hired. Total output increases by 110 compared to 130 when the second
worker is hired. This implies that the amount of labor needed to produce the same amount
of output has increased. For each unit of output that is produced between 80 and 210,
.008 unit of labor is required (1/130). To increase output by one unit between 210 and
320, the firm needs .009 unit of labor (1/110). This implies marginal cost must be
increase when output expands beyond 210 because the amount of labor needed per unit of
output is going up. In the table above MC increases from $.077 to $.091.
3. This curve could not be a short run variable cost curve for two reasons. It does not go
through the origin. Variable cost is zero when production is zero. The curve is also not
consistent with the principle of diminishing returns. Marginal cost must increase as
output increases. The curve implies marginal cost will decrease.
4a. increase in property tax
$
mc
Only the atc shifts. Property
tax increases the fixed
costs.
atc2
atc1
avc
mc1
b.
$
q
mc
atc1
avc1
All cost curves shift up. atc
avc
q
c. technological change
mc
mc1
atc
avc
atc1
avc1
q
All cost curves shift down. 5. The statement is false. Marginal cost could be increasing and still be below average
cost. If marginal cost is less than average cost, average cost will fall. It does not matter
whether marginal cost is increasing or decreasing.