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 " O"wher wher required. Round average inventory row, Inventory cost row, and Total row values to 1 decimal.) 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 " O"wher wher required. Round average inventory row, Inventory cost row, and Total row values to 1 decimal.)