(b)readers Question: A monopolist operates under a production technology which allows the production of any output level at a constant average cost of $5 per unit. This monopolist sells into two distinct markets the demand curves for which are:Q1 = 55 – P1 (for market one) and Q2 = 70 – 2P2 (for market 2).If this monopolist operates so as to maximize total profit then calculate:
(i) Total output;
(ii) The quantity sold in each market;
(iii) The price charged in each market;
(iv) The monopolist’s total profit.

The Demand Curve equals the average revenue curve.
We need to find out the Marginal revenue Curve
The Marginal Revenue curve is twice as steep.
- If Q.D = 55 – P1
MR = 55 -2P1
The next step is to work out profit maximisation.
Profit Maximisation for a Monopolist
- Profit Maximisation occurs where MR=MC
In this example MC = $5 (a constant average cost means the MC=AC)
Therefore, $5 = 55 – 2P1
2P = 50
Therefore, P=25
To find out the Quantity we put 25 into the equation
Q=55-25
Q=30
To Calculate Profit for A Monopoly
Profit = Total revenue – Total Cost
Total Revenue = 25*30 = 750
Total Cost = 5 * 30 = 150
- Therefore, total profit for this section is = 600 (assuming there is no fixed cost)






4 comments ↓
Thank you!
I had a similar question due tomorrow, and you’ve been a lifesaver. I was completely lost before
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pueng khammala ( teacher from Souphanouvong University , Luang Prabang province, Laos)
this answer is totally wrong. the first equation should be altered to P1=55-Q1 and then calculate MR, which should be 55-2Q1.
it is nice in a glance..but more clarfication is needed.
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