Dec 31, 2018	Dec 31, 2017	Dec 31, 2016	Dec 31, 2015
Return on Sales
Gross profit margin	19.42%	18.55%	14.57%	14.59%
Operating profit margin	11.85%	11.01%	6.17%	7.74%
Net profit margin	10.34%	8.78%	5.18%	5.39%
Return on Investment
Return on equity (ROE)	3,085.55%	2,309.01%	599.14%	81.70%
Return on assets (ROA)	8.91%	8.88%	5.44%	5.48%
Source: Based on data from Boeing Co. Annual Reports

A.	Boeing Co., short-term (operating) activity ratios
		Dec 31, 2018	Dec 31, 2017	Dec 31, 2016	Dec 31, 2015
	Turnover Ratios
	Inventory turnover	1.30	1.71	1.87	1.74
	Receivables turnover	26.07	8.88	10.71	11.03
	Payables turnover	6.30	6.23	7.21	7.59
	Working capital turnover	16.21	10.50	7.66	5.39
	Average No. of Days
	Average inventory processing period	280	213	195	210
	Add: Average receivable collection period	14	41	34	33
	Operating cycle	294	254	229	243
	Less: Average payables payment period	58	59	51	48
	Cash conversion cycle	236	195	178	195

calculate inventory turnover, operating margin, working capital and operating margin. Explain the value of understanding why inventory balances, inventory turnover, cost of goods sold, operating margin, and working capital are important metrics for Cost Accounting. Label your work in Excel to assist those who read your work.

for the years 2018,2017,2016,2015