Saturday, 12 April 2014



CHAPTER 7
                                                                                        
COST THEORY AND ESTIMATION


1. Fairweather Construction, Inc., has the following short-run total cost schedule:
Q             0       1      2       3       4       5      6      7      8      9      10       11
TC        100   106  109  110  112  115   119  124  130 137  145     155
(i) What is the firm's average fixed cost when Q = 5?
(ii) What is the firm's average variable cost when Q = 4?
(iii) What is the firm's average total cost when Q = 4?
(iv) What is the firm's marginal cost when Q = 10?
(v) At what level of output does the firm begin to experience diminishing returns?

Solution:
(i) AFC = 100/5 = 20 when Q = 5.
(ii) AVC = 12/4 = 3 when Q = 4.
(iii) ATC = 112/4 = 28 when Q = 4.
(iv) MC = (145 − 137)/(10 − 9) = (45 − 37)/(10 − 9) = 8 when Q = 10.
(v) MC is at a minimum when Q = 3. Therefore, diminishing returns set in when
Q > 3.


2. Fairview Construction, Inc., has the following short-run total cost schedule:
Q          0       1       2       3       4       5       6       7       8        9       10        11
TC       50    58     62     64     65    67      71    78     88    102    121       146
(i) What is the firm's average fixed cost when Q = 5?
(ii) What is the firm's average variable cost when Q = 7?
(iii) What is the firm's average total cost when Q = 8?
(iv) What is the firm's marginal cost when Q = 9?
(v) At what level of output does the firm begin to experience diminishing returns?

Solution:
(i) AFC = 50/5 = 10 when Q = 5.
(ii) AVC = 28/7 = 4 when Q = 7.
(iii) ATC = 88/8 = 11 when Q = 8.
(iv) MC = (102 − 88)/(9 − 8) = (52 − 38)/(9 − 8) = 14 when Q = 9.
(v) MC is at a minimum when Q = 4. Therefore, diminishing returns set in when
Q > 4.

3. Oceanview Construction, Inc., has the following short-run total cost schedule:
Q      0       1       2       3       4       5       6        7       8       9       10       11
TC   75    85      91    94     95     98    104   114   129   151   181     221
(i) What is the firm's average fixed cost when Q = 5?
(ii) What is the firm's average variable cost when Q = 4?
(iii) What is the firm's average total cost when Q = 10?
(iv) What is the firm's marginal cost when Q = 8?
(v) At what level of output does the firm begin to experience diminishing returns?

Solution:
(i) AFC = 75/5 = 10 when Q = 5.
(ii) AVC = 20/4 = 5 when Q = 4.
(iii) ATC = 181/10 = 18.1 when Q = 10.
(iv) MC = (129 − 114)/(8 − 7) = (54 − 39)/(8 − 7) = 15 when Q = 8.
(v) MC is at a minimum when Q = 4. Therefore, diminishing returns set in when
Q > 4.


4. Farview Construction, Inc., has the following short-run total cost schedule:
Q       0       1       2       3       4       5        6       7       8       9       10       11
TC   30      38     43     46    48     52      59     70     87    112   147     197
(i) What is the firm's average fixed cost when Q = 10?
(ii) What is the firm's average variable cost when Q = 4?
(iii) What is the firm's average total cost when Q = 7?
(iv) What is the firm's marginal cost when Q = 9?
(v) At what level of output does the firm begin to experience diminishing returns?

Solution:
(i) AFC = 30/10 = 3 when Q = 10.
(ii) AVC = 18/4 = 4.5 when Q = 4.
(iii) ATC = 70/7 = 10 when Q = 7.
(iv) MC = (112 - 87)/(9 - 8) = (82 - 57)/(9 - 8) = 25 when Q = 9.
(v) MC is at a minimum when Q = 4. Therefore, diminishing returns set in when
Q > 4.


5. Tetrangle Manufacturing has fixed costs of $2,160 per day. The firm manufactures bicycle component upgrade kits. The kits have a short-run average variable cost of $48 and are sold for $66 each.
(i) What is the breakeven level of daily output for the firm?
(ii) What is the degree of operating leverage when daily output is Q = 170?

Solution:
(i) The breakeven level of daily output for the firm is 2160/(66 − 48) = 120.
(ii) The degree of operating leverage (DOL) when daily output is Q = 170 is:
DOL = {(170)(66 − 48)}/{(170)(66 − 48) − 2160} = 3.4


6. Triangle Manufacturing has fixed costs of $2,000 per week. The firm manufactures tricycle kits. The kits have a short-run average variable cost of $25 and are sold for $35 each.
(i) What is the breakeven level of weekly output for the firm?
(ii) What is the degree of operating leverage when weekly output is Q = 250?

Solution:
(i) The breakeven level of daily output for the firm is 2000/(35 − 25) = 200.
(ii) The degree of operating leverage (DOL) when daily output is Q = 250 is:
DOL = {(250)(35 − 25)}/{(250)(35 − 25) − 2000} = 5


7. Bob and Bill are college students. They are trying to decide what to do over the next summer. Bob's father has suggested that they both come and work at his plastics manufacturing company where each will earn $3,600 over the summer. Bill's father, who runs the local farmer's market, suggests that they go to a local resort area and sell fresh fruit and vegetables to tourists. Their markup on the produce would be 25 percent, so each $1.00 of revenue would involve a variable cost of $0.80. In addition to purchasing the produce, they would have to rent a location. The cost to rent a small roadside stand
for the summer is $2,400.
(i) How many dollars worth of produce will they have to sell in order to break even in an accounting sense?
(ii) How many dollars worth of produce will they have to sell in order to break even in an economic sense?

Solution:
(i) 2400/(1.00 − 0.80) = $12,000
(ii) (2400 + 3600 + 3600)/(1.00 − 0.80) = $48,000


8. Barb and Cheryl are college students. They are trying to decide what to do over the next summer. Barb's mother has suggested that they both come and work at her plastics manufacturing company where each will earn $5,250 over the summer. Cheryl's mother, who runs the local farmer's market, suggests that they go to a local resort area and sell fresh fruit and vegetables to tourists. Their markup on the produce would be one-third, so each $1.00 of revenue would involve a variable cost of $0.75. In addition to purchasing the produce, they would have to rent a location. The cost to rent a small roadside stand
for the summer is $2,500.
(i) How many dollars worth of produce will they have to sell in order to break even in an accounting sense?
(ii) How many dollars worth of produce will they have to sell in order to break even in an economic sense?

Solution:
(i) 2500/(1.00 − 0.75) = $10,000

(ii) (2500 + 5250 + 5250)/(1.00 − 0.75) = $52,000

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