Consecutive five-year balance sheets and income statements of Mary Lou Szabo Corporation are as follows:

Required
a. Compute the following for the years ended December 31, 2009-2011:
1. Net profit margin
2. Total asset turnover
3. Return on assets
4. DuPont return on assets
5. Operating income margin
6. Operating asset turnover
7. Return on operating assets
8. DuPont return on operating assets
9. Sales to fixed assets
10. Return on investment
11. Return on total equity
12. Return on common equity
13. Gross profit margin

b. Briefly comment on profitability and trends indicated in profitability. Also comment on the difference in results between using the average balance sheet figures and year-end figures.