Using the data in the following? table, and the fact that the correlation of A and B is 0.02?, calculate the volatility? (standard deviation) of a portfolio that is 80% invested in stock A and 20% invested in stock B.
Stock A Stock B
2005 -12 16
2006 13 20
2007 8 7
2008 -1 -1
2009 5 -12
2010 6 15
The standard deviation of the portfolio is?