Please solve by hand and show all steps:

4. Every investor in a CML-efficient portfolio holds the risk-free asset, or the market portfolio, or some combination of the risk-free asset and the market portfolio. Assume that the standard deviation of the market portfolio is 30% and that the expected rate of return of the portfolio is 15%. What proportion of the following investor's wealth would you suggest investing in the market portfolio and what proportion in the riskless asset? The risk-free rate is 5%. a. an investor who desires a portfolio with no standard deviation; b. an investor who desires a portfolio with a standard deviation of 15%; c. an investor who desires a portfolio with a standard deviation of 30%; d. an investor who desires a portfolio with a standard deviation of 45%; e. an investor who desires a portfolio with an expected return of 12%