Suppose there is an investor with a very high risk tolerance. They could invest $100\%$ of their wealth in a stock fund with $=17\%$ and $E(r)=15\%,$ or they could borrow, and invest in the Optimal Risky Portfollo which has $=12\%$ and $E(r)=12\%$ Leverage would give them a higher $E(r)$ but with the same standard deviation as the stock fund $(17\%),$ if they can get a good borrowing rate.

a$.$ Assuming they can borrow at the T$-$Bill $($risk$-$free$)$ rate of $2\%,$ calculate the weights for the investor to create their Complete Portfolio. $(3$ points$)$

b$.$ Calculate the Expected Return for this Complete Portfolio. $(2$ points$)$

c$.$ Calculate the maximum interest rate at which the investor would be willing to borrow before they decided to just invest $100\%$ in the Stock fund $($assuming the same weights as you calculated in Part a$).$ In other words, calculate the breakeven borrowing rate. Show your work. If you use Solver in Excel, provide a screenshot and explain your setup. $(5$ points$)$