$7.$ Consider the following six investments:

Investment E$($r$)\%$ s $(\%)$

$1152$

$2124$

$3104$

$4102$

$5205$

$651$

a$)$ Use a Risk$/$Return diagram to determine which investment is dominant or efficient for an investor who uses the $$mean$-$variance criterion$.$

b$)$ How would the choice differ for $($i$)$ an investor who aimed to maximise expected rate of return, ignoring risk, $($ii$)$ one who sought to minimise risk, ignoring expected rate of return?