$($b$)$ The following information describes the expected return and risk relationship for two stocks.

$\backslash$table$[[$Year$,$Stock T$,$Stock B$],[1,0\mathrm{.}22,0\mathrm{.}10],[2,0\mathrm{.}11,0\mathrm{.}05],[3,-0\mathrm{.}15,-0\mathrm{.}11],[4,-0\mathrm{.}06,0\mathrm{.}04],[5,0\mathrm{.}18,0\mathrm{.}07]]$

$($i$)$ Calculate the arithmetic mean rate of return for Stock $T$ and $B.$

$(10$ Marks$)$

$(10$ Marks$)$

$($iii$)$ Calculate the standard deviation of the annual rate of return for Stock T and B$.$ Which stock is preferable in terms of risk$-$return trade$-$off?

$(20$ Marks$)$