The S&P 500 earned an average 13.9% per year with a standard deviation of 15.1%. Based upon these assumptions, and a 4% risk-free rate, suppose an investor created an investment portfolio with 80% invested in the S&P 500 and 20% devoted to Treasury Bills. If the covariance between returns on T-bills and the S&P 500 is zero, calculate the portfolio expected return and standard deviation.