In: Economics
2. For the following total revenue and total cost functions of a firm:
TR = 800Q – 10Q2
TC = (2/3)Q3 -30Q2 + 672Q +4000
(a) Determine the level of output at which the firm maximizes total profit
(b) Calculate the profit
(need step by step, please)
a) | For a firm's supply under perfect competition, a firm will maximize profits when it produces at that level | |||||||||
where Marginal cost = price | ||||||||||
MC = P | ||||||||||
For perfect competitors , P = MR (marginal revenue) | ||||||||||
TR = 800Q - 10Q^2 | ||||||||||
Marginal revenue (MR) is the first derivative of the Total revenue(TR) | ||||||||||
MR = 800 - 20Q | ||||||||||
TC (Total cost) = (2/3)Q^3 - 30Q^2 +672Q + 4000 | ||||||||||
MC (marginal cost) = 2Q^2 - 60Q + 672 | ||||||||||
We find Q when MR = MC | ||||||||||
800 - 20Q = 2Q^2 - 60Q + 672 | ||||||||||
2Q^2 - 40Q -128 = 0 | ||||||||||
Q^2 - 20Q -64 = 0 | ||||||||||
Solving the quadratic equation | ||||||||||
(20 +/- (20^2 +4*64)^(1/2))/2 | ||||||||||
(20 +/- 25.6)/2 | ||||||||||
45.6/2 | ||||||||||
22.8 | ||||||||||
Q = 22.8 | ||||||||||
b) | Profit = TR - TC when Q = 22.8 | |||||||||
TR - TC = | ||||||||||
(-(2/3)Q^3 +20Q^2 +128Q - 4000 | ||||||||||
Profit = $1413.63 | ||||||||||