What is the expected return and standard devaition of a portfolio consisting of $7200 invested in a risk-free asset with an 7.9 percent rate of return, and $2400 invested in a risky security with a 19.9 percent rate of return and a 24.9 percent standard deviation?

a) 6.225 percent , 10.90 percent

b) 16.90 percent , 18.675 percent

c) 18.675 percent , 16.90 percent

d) 10.90 percent , 6.225 percent