Problem:
The DuPont formula defines the net return on shareholder's equity as a function of operating margin, asset turnover, interest burden, financial leverage, and income tax.
Using data from the financial reports of Southwest Airlines, Caterpillar, and Proctor and Gamble calculate the return on equity using the DuPont ratio for years ending 2005-2007 (show all work).
Briefly discuss the impact of the changes in asset turnover and financial leverage on ROE over the the three years.