Production in the country of Laboristan can be characterized
Solution
Y = 2K0.2L0.8
(a)
MPL = dY / dL = 2 x 0.8 x (K / L)0.2 = 1.6 x (K / L)0.2
MPK = dY / dK = 2 x 0.2 x (L / K)0.8 = 0.4 x (L / K)0.8
(b)
Diminishing marginal product of labor states that as more of labor is used, MPL decreases.
Initial L = 1,000 & K = 200
Initial MPL = 1.6 x (K / L)0.2 = 1.6 x (200 / 1,000)0.2 = 1.6 x (0.2)0.2 = 1.6 x 0.72 = 1.16
Let L increase by 1,000 and new level of L = 2,000
New MPL = 1.6 x (K / L)0.2 = 1.6 x (200 / 2,000)0.2 = 1.6 x (0.1)0.2 = 1.6 x 0.63 = 1.01
So, as L has increased, MPL has declined.
(c)
Total cost, C = wL + rK = 1,000w + 200r
Also, in optimality, (MPL / MPK) = w/r
1.6 x (K / L)0.2 / 0.4 x (L / K)0.8 = w/r
4 x (K / L) = w/r
4 x 200 / 1,000 = w / r
w / r = 0.8
Total cost = 1,000w + 200r = 1,000 x 0.8r + 200r = 1,000r
[To find numerical value of total cost, we need value of either w or r].
(d)
As amount of labor increases, higher supply of labor lowers the wage rate. Amount of capital remaining unchanged, real rental rate increases relative to real wage rate.
NOTE: First 4 sub-questions are answered.
