Answer: 1.9%
Explanation:
First derive the Market return as this is needed in the Capital Asset Pricing Model by using the same model:
Required return = Risk free rate + Beta * ( market return - Risk free rate)
Using stock Y:
12.4% = Risk free rate + 1 * (market return - Risk free rate)
12.4% = Rf + market return - Rf
Market return = 12.4%
Use this to calculate the Risk free rate:
Stock Z:
8.2% = Rf + 0.6 * (12.4% - Rf)
8.2% = Rf + 7.44% - 0.6Rf
Rf - 0.6Rf = 8.2% - 7.44%
0.4Rf = 0.76%
Rf = 0.76% / 0.4
= 1.9%