please EXPLAIN how you came to the answers. thanks!

8. Herbert Investments wants to prepare a portfolio made up of four socks They turn at lowest possible rik D08 RST ZIR MEAN RETURN 0.094 0.1260.107 0.189 0.163 0049 STDEV OF RETURN (a) 0.011 0.150 CORRELATIONS IR) BBX DOB ZTR BBX 0.12 0.09 0.18 DOB 0.12 0.09 0.18 0.29 AST 0.29 0.43 0.67 0.43 ZTR your spreadsheet model with the optimal solution. BBX: DOB: RST: ZTR: Portfolio standard deviation: a. Find the optimal solution using an Excel spreadsheet model and Solver. Attach