10.2 Stock A has an expected rate of return of 8 percent, a standard deviation of 20 percent, and a market beta of 0.5. Stock B has an expected rate of return of 12 percent, a standard deviation of 15 percent, and a market beta of 1.5. Which investment is riskier? Why? (Hint: Remember that the risk of an investment depends on its context.)

If Investment made on Diversified Portfolio than Stock B is more risky then compared to stock A as per CAPM

Whereas Investment is only on one stock then more risky investment is Stock A as per Coeffient of Variation