Question $1$:

A portfolio is composed of two stocks, A and B$.$ Stock A has a standard deviation of return of $5\%$ while stock B has a standard deviation of return of $15\%.$ The correlation coefficient between the returns on A and B is $0\mathrm{.}5.$ Stock A comprises $40\%$ of the portfolio while stock B comprises $60\%$ of the portfolio. Calculate the variance of return on the portfolio.