Using the data in the following table, and the fact that the correlation of A and B is 0.26, calculate the volatility (standard deviation) of a portfolio that is 50% invested in stock A and 50% invested in stock B. Year 2008 2009 2010 2011 2012 2013 Realized Returns Stock A Stock B -7% 24% 13% 22% 7% 9% -4% -2% - 11% 6% 22% 1% The standard deviation of the portfolio is %. (Round to two decimal places.)