ECON 3101 - Intermediate Microeconomics Summer 2022 Problem Set 2
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ECON 3101 - Intermediate Microeconomics
Summer 2022
Problem Set 2
1. (POINTS: 21)
Consider the production functions below . For each, state and prove whether it is con-
stant/increasing/decreasing returns to scale.
(a) F(K,L) = K L (Points: 7)
(b) F(K,L) = min{2K, 4L} + 40 (Points: 7)
(c) F(K,L) = 4K + 5L (Points: 7)
2. (POINTS: 19)
Consider the following production function:
1 2
F(K,L) = 2K 3 L 3
(a) Graph at least two isoquants and clearly identify at least one point in each. (Points:
7)
(b) Obtain the marginal rate of technical substitution (be sure to present all steps in your calculation). (Points: 6)
(c) Obtain the elasticity of substitution (be sure to present all steps in your calculation).
(Points: 6)
3. (POINTS: 15)
Explain why, unlike utility functions, production functions are cardinal, i.e., not only the order but also the output value matters.
4. (POINTS: 45)
The production of bikes require a fixed proportion of machines and workers, and the increase
in the quantity of just one of the inputs cannot increase production . More specifically, the
ideal combination of inputs is 5 workers for each machine, and if the firm uses the input plan
(K, L) = (1, 5), it will obtain exactly one bike.
(a) What is the production function for this firm? (Points: 5)
(b) Set up the short run cost minimization problem when K = K¯ . (Points: 5)
(c) Let q be the minimal amount of output. What is the set of feasible labor choices if K¯ < q? Explain. (Points: 5)
Now assume K¯ > q.
(d) Solve for the short run optimal amount of labor, Lsr(q) and for the short run minimized cost, Csr(q, w, r, K¯ ). (Points: 8)
(e) Set K¯ = 3 , q = 2 , r = $2, and w = $1 . Draw a LK-diagram that includes (i) the iso- quant IQ(2), (ii) the point (Lsr(q), K¯ ), and (iii) the isocost passing through this point.
(Points: 5)
(f) Setup the long run cost minimization problem and solve for the optimal input choices L ∗ (q, w, r), K (q∗ , w, r), and the minimized cost C (q∗ , w, r). (Points: 8)
(g) Set q = 2, r = $2, and w = $1. Draw a LK-diagram that includes (i) the isoquant IQ(2), (ii) the point (L∗ , K ), and (iii) the isocost passing through this point∗ . (Points: 5)
(h) How much is Csr(2, 1, 2, 3) −C ∗ (2, 1, 2)? Explain the sign (positive/zero/negative) of this quantity. (Points: 4)
2022-06-27