Answer:
c. $400
Explanation:
The marginal revenue curve can be written as a function of the price as follows:
[tex]Q = 6000 - 5P \\MR = 1200 - 0.3Q\\MR = 1200 - 0.3*(6000 - 5P)\\MR = -600+1.5P[/tex]
The value of P which yields a marginal revenue of zero is the profit-maximizing price, since there would be no added revenue from selling an extra unit at that level of output:
[tex]0 = -600+1.5P\\P=\frac{600}{1.5}\\P = \$400[/tex]
The profit-maximizing price is $400.