The securities of companies Z and Y have the following expected returns and standard deviations:
.................................................Z.............Y
Expected return (%)........................15............35
Standard deviation (%)....................20............40
If the correlation coefficient between the two securities is +0.25, calculate the expected return and standard deviation for the following portfolios:
(a) 100 per cent Z;
(b) 75 per cent Z and 25 per cent Y;
(c) 50 per cent Z and 50 per cent Y;
(d) 25 per cent Z and 75 per cent Y;
(e) 100 per cent Y.