Calculate the standard deviation and return of a portfolio consisting of 60% of Security A and 40% of Security B.  Assume correlation coefficient between stock A and stock B is 0.55. Interpret the benefit of portfolio over individual stock investment (in case of security A and B).\n

Year    Security A return(%) Security B return(%) 

2015               10                                 18 

2016               12                                 15 

2017                9                                  11 

2018               10                                   9 

2019                5                                   7