Answer:
a) Expected return of portfolio = (12*.5 ) +(3*.5) = 6 + 1.5 = 7.5%
b)Beta of risk free asset = 0 (as there is no risk involved)
Let weight of stock = X
Weight of risk free asset = 1-X
Portfolio beta = (Beta of stock *Ws) +(Beta of risk free asset *Wd)
0.98 = (1.75 *X)+(0 *[1-X)]
0.98 = 1.75x + 0
X = 0.98 /1.75
X = 0.56
Weight of stock = 0.56 or 56%
Weight of risk free asset = 1 - 0 .56 = 0.44 or 44%
c) Expected rate = Rf+Beta *(Market rate - Rf)
12% = 3% + 1.75*(Market rate - RF)
(Market rate - Rf) = 9%/1.75
(Market rate - Rf) = 5.1429%
Now expected rate is given as 9%
Expected rate = Rf + Beta*(Market rate - Rf)
9% = 3% + Beta*(Market rate - Rf)
Beta = 6%/5.1429%
Beta = 1.1667
d) 3.50 = [1.75*X ] + [0*(1-X)]
3.5 = 1.75X + 0
X = 3.5/1.75
X = 2
Weight of stock = 2 or 200%
Weight of risk free asset = 1 - 2 = -1 or -100%