A stock had returns of 15 percent, 15 percent, 18 percent. -1 percent, 18 percent, and 11 percent over the last six years. What is the arithmetic return for the stock? 12.67% 12.77% 15.20% 12.87% 13.30% What is the geometric return for the stock? 12.47% 12.91% 15.14% 12.57% 12.27%