Suppose you are a mutual fund manager. Your fund owns a risky portfolio with an expected rate of return of 20% and a standard deviation of 30%. The T-bill rate is 5%. Assume a client decides to invest in your risky portfolio a proportion (y) of his total investment budge and invest in a proportion (1-y) of risk-free T-bills.

(i) If his overall portfolio will have an expected return 15%, then how much is the proportion y?

(ii) How much is the standard deviation of this clients overall portfolio?