b$.$ Compare the costs to a level plan that uses inventory to absorb fluctuations. Inventory carrying cost is $$4$ per engine per month. Backlog cost is $$144$ 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. $($Negative amounts should be indicated by a minus sign. Leave no cells blank $-$ be certain to enter $"0"$ wherever required. Round average inventory row, Inventory cost row, and Total row values to $1$ decimal.$)$

$\backslash$table$[[$Period$,1,2,3,4,5,6,7,8,$Total$],[$Forecast$,130,133,132,128,133,125,140,135,1,056],[\backslash$table$[[$Output$],[$Reqular$]]],[$Output $-$ Forecast$],[],[$Inventory$],[$Beginning$,,,,,,,,,],[$Ending$,,,,,,,,,],[$Average$,,,,,,,,,,],[$Backlog$,,,,,,,,,],[$Costs$],[$Output$],[$Regular$],[$Inventory$],[$Backorder$],[$Total$,,,,$f$,,,,,]]$