You find a certain stock that had returns of 14 percent, -27 percent, 19 percent, and 21 percent for four of the last five years, respectively. The average return of the stock over this period was 9.5 percent. What is the standard deviation of the stock's returns?

11.67 percent
	12.90 percent
	14.14 percent
	18.47 percent
	20.59 percent