I can't seem to solve this homework problem, could you please help?

Using the data in the following table, a , calculate the volatility (standard deviation) of a portfolio that is 77% invested in stock A and 23% in stock B. The volatility of the portfolio is |:|%. (Round to two decimal places.) 0 Data Table (Click on the following icon 21 in order to copy its contents into a spreadsheet.) Year 2010 2011 2012 2013 2014 Stock A - 13% 5% 4% - 2% 4% Stock B 24% 24% 4% - 8% - 14%