United Financial Corp had a return on equity of 15%. The corporation's earnings per share was $6.00, its dividend payout ratio was 40% and its profit-retention rate was 60%. If these relationships continue, what will be united financial corp's internal growth rate?

**My professor gave us the answer - 8.6%; however, I cannot figure out how to get there. I've been using the following formula: (1 - Pay Out Rate) * ROE

This gives me 9%. Could someone please explain?