Final answer:
The industry supply curve at prices greater than $2 is q = 400p.
Step-by-step explanation:
In this scenario, the industry supply curve can be determined by adding up the quantities supplied by each firm at prices greater than $2. For the first 100 firms, the cost curve is c(q) = 2 + q^2/2 and the marginal cost curve is MC(q) = q. At a price greater than $2, each firm will choose a level of output where MR (marginal revenue) equals MC. MR = P since there is no price discrimination. Let's first calculate the quantity supplied by the first group of firms:
MR = MC = q


Solving for q, we get q = -2 or q = 4. Since the quantity can't be negative, we have q = 4. Therefore, the first 100 firms will supply a total quantity of 100 * 4 = 400 at prices greater than $2.
For the next 80 firms, the cost curve is c(q) = q^2/10 and the marginal cost curve is MC(q) = q/5. Following the same process as above, we calculate the quantity supplied by the second group of firms:
MR = MC = q/5


Solving for q, we get q = -5 or q = 10. Since the quantity can't be negative, we have q = 10. Therefore, the next 80 firms will supply a total quantity of 80 * 10 = 800 at prices greater than $2.
Adding up the quantities supplied by both groups, the industry supply curve at prices greater than $2 is q = 400 + 800 = 1200p. Therefore, the correct answer is option c. q = 400p.