Answer:
The risk premium appropriate for this security is 4%.
Explanation:
The returns vary by only half as much as the market index which means that the security half as risky as the market.
The risk-premium for the security should be half of the market risk premium.
Market risk premium is calculated by = Expected return on the market - Risk free rate
Market risk premium = 13% - 5% = 8%
The risk premium on the security would be 8% / 2 = 4%