Continuing the previous problem (with capacity 300 at plant 2), suppose we want to see how much extra capacity and extra demand we can add to plant 1 and region 2 (the same amount to each) before the total shipping cost stops decreasing and starts increasing.

Use SolverTable appropriately to find out. (You will probably need to use some trial and error on the range of input values.) Can you explain intuitively what causes the total cost to stop decreasing and start increasing?