Cost of Capital. The Conner Company has the following capital structure:
| Mortgage bonds, 6% | $ 20,000,000 | 
| Common stock (1 million shares) | 25,000,000 | 
| Retained earnings | 55,000,000 | 
| 
 | $100,000,000 | 
Mortgage bonds of similar quality could be sold at a net of 95 to yield  6½ percent. Their common stock has been selling for $100 per share. The  company has  paid 50 percent of earnings in dividends for several years and intends  to continue the policy. The current dividend is $4 per share. Earnings  are growing  at 5 percent per year. If the company sold a new equity issue, it would  expect to net $94 per share after all costs. Their marginal tax rate is  50 percent.  Conner wants to determine a cost of capital to use in capital  budgeting. Additional projects would be financed to maintain the same  relationship between  debt and equity. Additional debt would consist of mortgage bonds, and  additional equity would consist of retained earnings. (a) Calculate the  firm's  weighted average cost of capital, and (b) explain why you used the  particular weighting system.