Please help me solve this!

Using the data in the following table, calculate the volatility (standard deviation) of a portfolio that is 74% invested in stock A and 26% in stock B. The volatility of the portfolio is % (Round to two decimal places.) Data table (Click on the following icon in order to copy its contents into a spreadsheet.) Year 2010 2011 2012 2013 2014 Stock A -4% 15% 4% - 10% 2% Stock B 23% 6% 31% - 5% - 6% 2015 15% 18% Print Done