Final answer:
The formula for the revenue function is R(q) = q * p. To find R(a), substitute a for q in the revenue function. The marginal revenue is calculated by taking the derivative of the revenue function with respect to q.
Step-by-step explanation:
(a) What is the formula for the revenue function?
The correct formula for the revenue function is R(q) = q * p.
(b) Find R(a).
To find R(a), we need to substitute a for q in the revenue function:
R(a) = a * p
R(a) = a * [(a^2/2400) + 1000]
(c) Find an expression equal to the marginal revenue.
The marginal revenue is calculated by taking the derivative of the revenue function with respect to q. In this case, the derivative is:
R'(q) = p + q * p'
where p' is the derivative of p with respect to q.
(d) Find the marginal revenue when the demand is q = 20.
To find the marginal revenue when q = 20, substitute 20 for q in the expression for R'(q):
R'(20) = p + 20 * p'