What's the answer? Thanks in advance!

Let's say Tim invested 70% of his money to buy ABC Corp.'s shares and 30% of his money to buy DEF Corp.'s shares in 2013. From 2014 to 2017, ABC Corp. generated the total return percentage of 15%,5%,20%,2%. DEF Corp. generated the total return percentage of 5%,6%,5%, and 6% during the same time period. What was the average rate of return for the portfolio (plain English: Tim's investment as a whole) from 2014 to 2017? 5.50% 7.00% 6.55% 8.12% Same facts as above: what's the portfolio's standard deviation? 1.45% 0.72% 8.48% 11.56%