If you could explain the answer that would be great!

1. Stock A has a beta of 0.9, and stock B has a beta of 0.5. You invest 0.7% of your capital in stock A, and the rest in stock B. What is the beta of the resulting portfolio?

I took (0.9x0.7)+(0.5x99.3)=0.5, but the correct answer is 0.8 and I don't know how they got that

2. Assume that the Pure Expectation Theory determines interest rates in the markets. Today's market rates for different maturities follow an interesting pattern. The spot rate for investing for 1 year is 5%. After that, the rate increases by 1% for each year. So, in general, the rate for year Y is simply 5% + 1%*(Y-1).

Given this information, what is the implied interest rate to invest for 1 year, starting in 3 years?