What is the expected return and standard deviation of a portfolio consisting of $3600 invested in a risk-free asset with an 6.7-percent rate of return, and $1200 invested in a risky security with a 18.7-percent rate of return and a 23.7percent standard deviation? 17.775 percent, 15.70 percent 15.70 percent, 17.775 percent 5.925 percent, 9.70 percent 9.70 percent, 5.925 percent