Changes

:When total revenue is maximized, then no additional revenue is possible.  Increasing output at that point must have marginal revenue of zero.

:When total revenue is maximized, then no additional revenue is possible.  Increasing output at that point must have marginal revenue of zero.

:"Marginal revenue must be zero when total revenue is maximized because marginal revenue is the additional revenue gained by selling one more unit. And total revenue is the revenue earned from all of your sales. If total revenue is maximized, that means you are earning all you can earn and selling all you can sell. Therefore, (since you can't sell anymore), you can't have marginal revenue (since that is revenue earned for selling one more unit)." (by student MGY)

:"Marginal revenue must be zero when total revenue is maximized because marginal revenue is the additional revenue gained by selling one more unit. And total revenue is the revenue earned from all of your sales. If total revenue is maximized, that means you are earning all you can earn and selling all you can sell. Therefore, (since you can't sell anymore), you can't have marginal revenue (since that is revenue earned for selling one more unit)." (by student MY)

9.  Provide, in your own words, the best definition of "public good" that you can.

9.  Provide, in your own words, the best definition of "public good" that you can.