Problem

Suppose that the market is made up of many identical firms. Each firm's Long-Run Average Cost curve is given by:

Average Costs $=((120 / Q)+3 Q)$

And their Marginal Cost curve is given by:
\[
M C=2 * 3 * Q
\]

Given this, what must be the Long-Run market price $\left(\mathrm{p}^{*}\right)$ if there exist free entry and exit of firms?
Note: round your answers to two decimal places.

Answer

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Answer

Therefore, the long-run market price must be \(\boxed{37.95}\)

Steps

Step 1 :Given the long-run average cost (LRAC) curve: \(\text{Average Costs} = \frac{120}{Q} + 3Q\)

Step 2 :To find the long-run market price, we need to find the minimum point on the LRAC curve. This is done by taking the derivative of the average cost function with respect to Q and setting it equal to zero.

Step 3 :The derivative of the average cost function is: \(\frac{d(\text{Average Costs})}{dQ} = -\frac{120}{Q^2} + 3\)

Step 4 :Setting this equal to zero gives: \(-\frac{120}{Q^2} + 3 = 0\)

Step 5 :Solving for Q gives: \(Q^2 = \frac{-120}{-3}\) which simplifies to \(Q^2 = 40\)

Step 6 :Taking the square root of both sides gives: \(Q = \sqrt{40} = 6.32\) (rounded to two decimal places)

Step 7 :Substituting \(Q = 6.32\) back into the average cost function gives the minimum average cost, which is the long-run market price: \(p^* = \frac{120}{6.32} + 3 * 6.32\)

Step 8 :Solving the above equation gives: \(p^* = 18.99 + 18.96\)

Step 9 :\(p^* = 37.95\) (rounded to two decimal places)

Step 10 :Therefore, the long-run market price must be \(\boxed{37.95}\)

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