In: Economics
SuperiorSharp Inc. produces scissors. Wages are $12 per hour and all the scissors-making equipment rents for a total of $36 per hour. The production function is Q = 30K0.75L0.25, where K and L denote its capital and labor inputs, respectively.
a. The firm is currently producing 3000 pairs of scissors and has determined (correctly) that the cost-minimizing quantities of labor and capital are 100 units of labor and 100 units of capital. Sketch this equilibrium, using isoquants and isocost lines, and label it A.
b. The firm now wants to increase output to 4200 pairs of scissors. If capital is fixed at K = 100 in the short run, how much additional labor will the firm require? Sketch in the new short run equilibrium on your graph, and label it B. How much does it cost the firm to produce 4200 pairs of scissors in the short run?
c. Find the optimal level of capital and labor required to produce 4200 pairs of scissors in the long run, and add the new long run equilibrium to your graph, labeling it C. How much will it now cost to produce 4200 pairs of scissors? Explain.
(a)
In following graph, initial equilibrium is at point A where isoquant Q0 is tangent to isocost line C0 with optimal input mix being (K0= 100, L0 = 100).
(b)
When K = 100 and Q = 4200,
30 x (100)0.75 x L0.25 = 4200
(100)0.75 x L0.25 = 140
L0.25 = 4.43
L = 384.16
Increase in L = 284.16 - 100 = 284.16
Total cost = wL + rK = 12 x 384.16 + 36 x 100 = 4609.92 + 3600 = 8209.92
In above graph, short run equilibrium is at point B where new isocost Q1 is tangent to C0 with new input mix being (K0 = 100, L1 = 384.16)
(c)
Cost is minimized when MPL/MPK = w/r = 12/36 = 1/3
MPL = Q/L = 30 x (K/L)0.75
MPK = Q/K = 30 x (L/K)0.25
MPL/MPK = K/L = 1/3
L = 3K
Plugging in production function,
30 x (K)0.75 x (3K)0.25 = 4200
30.25 x (K)0.75 x K0.25 = 140
K = 106.38
L = 3 x 106.38 = 319.14
Total cost = 12 x 319.14 + 36 x 106.38 = 3829.68 + 3829.68 = 7659.36
In above graph, long run equilibrium is at point C where new isocost Q1 is tangent to new isocost line C1 with new input mix being (K1 = 106.38, L2 = 319.14).