Answer:
What is marginal revenue when quantity is 30 ? 30? 
= ($2,400 - $1,350) / (30 - 15) = $900 / 15 = $70  
What is marginal cost when quantity is 60 ? 60? 
= ($3,150 - $2,250) / (60 - 45) = $900 / 15 = $60 
If this firm is a monopoly, at what quantity will profit be maximized? 
a monopoly maximizes its accounting profit when marginal revenue = marginal cost, in this case they both equal $50 per unit when total output is 45 units
If this is a perfectly competitive market, which quantity will be produced? 
a perfectly competitive firm maximizes its accounting profit when marginal revenue = marginal cost, in this case they both equal $50 per unit when total output is 45 units
Comparing monopoly to perfect competition, which statement is true? 
- The consumer surplus is smaller with a monopoly. 
- The monopoly's price is higher.
In a monopoly, output is smaller than the perfectly competitive output. The price charged by a monopolist is also higher. This also results in lower consumer surplus with a monopoly. 
Explanation:
Quantity      Price       Total Revenue            Total Cost 
15                 90                   1350                         900 
30                80                   2400                      1500 
45                70                    3150                      2250 
60                60                  3600                       3150 
75                50                   3750                      4200 
90                40                  3600                      5400