How do I figure out the total revenue and marginal revenue. Do I just multiply 20+q/200 by q getting 20q+q^2/200? If so, the partial derivative is 20+q/100? Equating that to 20+q/200 gets q=0. What's going on?

Greg,

I have the same answers as you for parts C and D of the Module 13 Homework.

For Part E, use the price P=22 that you calculated in part D. Plug that value of P=22 into the market demand curve P=122-Q/4 and then solve for Q. That will tell you the total industry demand quantity Q.

For Part F, divide the industry quantity (which is your answer to part E) by each firm's quantity (which is your answer to part C) to find the total number of firms competing in this industry. I got an answer of 4 firms competing in the industry for Part F.