Resolved the doubt… Thanks for the help
You forgot class vi algebra. (a+b)^2
14,14%=(0.30.2)^2+(0.70.12)^2+ 20.30.20.70.12*correlation
To the right of the equal sign you have a formula for the variance of returns for the portfolio; to the left you have the standard deviation of the portfolio’s returns.
Ooops…you are right.
you are missing the 2 in the formula is must be (.3^2*.2^2+.7^2*.12^2+2*.7*.3*.2*.12*1)^.5
In the special case where correlation = 1, the standard deviation of the portfolio will be the weighted average of the individual assets’ standard deviations.
In this case, 0.3(0.20) + 0,7(0.12) = 14.4%, so the correlation is therefore 1