The following table shows the expected returns on three assets X$,$ Y$,$ Z for the period $2018-2022.$ Assume that the investor is willing to form a portfolio of X and Y or X and Z$.$ He also is planning to invest $2/3$ of his investment funds in X and $1/3$ in Y or Z$.$

Year Rx $(\%)$ Ry $(\%)$ Rz $(\%)$

$20188248$

$2019102012$

$2020121616$

$2021141220$

$202216824$

Answer the following questions accordingly:

$1.$ Calculate the average expected return on portfolio X and Y$.$

$2.$ Calculate the average expected return on portfolio X and Z$.$

$3.$ Calculate the standard deviation of portfolio X and Y$.$

$4.$ Calculate the standard deviation of portfolio X and Z$.$

$5.$ What is your advice to this investor?