You have given the following forecasts for the economy and Stock A: (1) the probability of having a recession next year is 30 percent, a normal economy is 55 percent, and an expansion is 15 percent, and (2) the price of Stock A will be $9 if the economy is in recession, $15 if the economy is normal, and $18 if the economy is in expansion. What is the ex ante standard deviation of Stock As returns if it is currently selling for $12?