Answer and Explanation:
A.
E(r) = y x R(rp) + (1-y)*rf
0.18 = y * 0.22+(1-y)*0.06
0.18 = 0.22y +0.06 -0.06y
Collect like terms
0.18-0.06 = 0.22y - 0.06y
0.12 = 0.16y
y = 0.12/0.16
= 0.75
= 75%
B.
Stock a = 31% x 0.75
= 0.2325
= 23.25%
Stock b = 36% * 0.75
= 0.27%
Stock c = 33% * 0.75
= 0.2475
= 24.75%
A total of all these stocks gives 100 percent
C.
We have standard deviation = 34%
Y * standard deviation
= 0.75 * 0.34
= 0.255
= 25.5%