b$.$ Compare the costs to a level plan that uses inventory to absorb fluctuations. Inventory carrying cost is $$2$ per engine per month.

Backlog cost is $$125$ per engine per month. There should not be a backlog in the last month. Set regular production equal to the

monthly average of total forecasted demand. Assume that using overtime is not an option.

Note: Negative amounts should be indicated by a minus sign. Leave no cells blank $-$ be certain to enter $"$O$"$ wherever required.

Round average inventory row, Inventory cost row, and Total row values to $1$ decimal.