A stock had returns of 7 percent, 5 percent, 2 percent, and 10 percent over the past 4 years. What is the standard deviation of this stock for the past four years?

A stock has returns of 7 percent, 14 percent, ?15 percent, and 19 percent for the past 4 years. Based on this information, what is the 95 percent probability range for any one given year?