Assume Intel's stock has an expected return of 26% and a volatility of 50%, while Coca-Cola's has an expected return of 6% and volatility of 25%. If these two stocks were perfectly negatively correlated (i.e., their correlation coefficient is -1),
a. Calculate the portfolio weights that remove all risk.
b. If there are no arbitrage opportunities, what is the risk-free rate of interest in this economy?