An Investor Wishes to Construct a Portfolio Consisting of a 70

An investor wishes to construct a portfolio consisting of a 70% allocation to a stock index and a 30% allocation to a risk free asset.The return on the risk-free asset is 4.5% and the expected return on the stock index is 12%.The standard deviation of returns on the stock index is 6%.Calculate the expected standard deviation of the portfolio.

A) 4.20%
B) 25.20%
C) 3.29%
D) 10.80%
E) 5.02%