Obi-wan forms an aggressive growth portfolio by investing 20% of his savings in GMstock, 21% in Nissanstock, 21% in Kiastock, 11% in an index fund, and the last 27% is allocated on a bond fund. Assume for simplicity that the index fund is a good proxy to the market portfolio and has a beta equal to 1, whereas the bond fund is a good proxy to the riskless asset. The beta of GM stock is 1.19, the beta of Nissanis 1.57, and the beta of Kiais 1.89. If the expected return of the market index is 13% and the risk-free asset yields 4%, what are the beta and the expected return of Obi-wan's portfolio?

What is the beta of the portfolio?

Please explain in detail, no excel all calculations