Using the data in the following table, and the fact that the correlation of A and B is 0.42, calculate the volatility (standard deviation) of a portfolio that is 50% invested in stock A and 50% invested in stock B. (Click on the following icon in order to copy its contents into a spreadsheet.) Year 2008 2009 2010 2011 2012 2013 Realized Returns Stock A Stock B -7% 28% 20% 20% 3% 11% -8% -9% 2% - 11% 14% 28% The standard deviation of the portfolio is %. (Round to two decimal places.)