Suppose investors can borrow and lend at the risk-free rate of 7%. Joyce Zoot wants the expected return of her total portfolio to be 15%. Her financial planner has told her that this will require her to invest some of her money in the risk-free asset and the rest in a risky asset (asset A) that has an expected return of 30%. With this investment plan, the risk (standard deviation) of Joyce’s complete portfolio will be 20%. What is the standard deviation of asset A?