Answer :
Answer:
The Beta of Replacement Stock is 1
Explanation:
First we need to find the Beta of Portfolio after selling the Stock A.
using following formula
it is assume that all stock has equally weighted hence stock A has weight of 10% since and remaining portfolio weight (100%-10%) = 90%
Portfolio beta = (R Pb x Weight) + ( Stock A Beta x Weight)
1.8 = ( R Pb x 0.9 ) + ( 2.0 x 0.1 )
1.8 = ( R Pb x 0.9 ) + 0.2
1.8 - 0.2 = ( R Pb x 0.9 )
1.6 = 0.9 R Pb
R Pb = 1.6 / 0.9 = 1.778
Now Using the same formula we will find beta of replacement stock.
Portfolio beta = (R Pb x Weight) + ( Replacement stock Beta x Weight)
1.7 = ( 1.778 x 0.9) + (Replacement stock Beta x 0.1)
1.7 = 1.6 + (Replacement stock Beta x 0.1)
1.7 - 1.6 = (Replacement stock Beta x 0.1)
0.1 = (Replacement stock Beta x 0.1)
Replacement Stock beta = 0.1 / 0.1
Replacement stock beta = 1