Please help! I've been trying to solve this and I can't seem to find the correct answer....

Using the data in the following table, , calculate the volatility (standard deviation) of a portfolio that is 72% invested in stock A and 28% in stock B. The volatility of the portfolio is %. (Round to two decimal places.) i Data Table - X (Click on the following icon @ in order to copy its contents into a spreadsheet.) Year 2010 2011 2012 2013 2014 2015 Stock A - 1% 6% 1% - 1% 3% 13% Stock B 18% 3% 23% - 6% - 8% 22% Print Done