Please show formula in excel

A THREE-ASSET PORTFOLIO PROBLEM \begin{tabular}{|l|r|r|r|} \hline & Stock A & Stock B & \multicolumn{1}{|c|}{ Stock C } \\ \hline Mean & 2.92% & 6.58% & 10.47% \\ \hline Variance & 4.96% & 4.57% & 3.91% \\ \hline Standard deviation & 22.28% & 21.38% & 19.77% \\ \hline Cov(rA,rB) & 0.77 & & \\ \hline Cov(rB,rC) & 0.95 & & \\ \hline Cov(rA,rC) & 0.86 & & \\ \hline \end{tabular} Portfolio proportions \begin{tabular}{|l|l|} \hline XA & 25% \\ \hline xB & 35% \\ \hline xC & 40% \\ \hline \end{tabular} Portfolio statistics Mean Variance Sigma A THREE-ASSET PORTFOLIO PROBLEM \begin{tabular}{|l|r|r|r|} \hline & Stock A & Stock B & \multicolumn{1}{|c|}{ Stock C } \\ \hline Mean & 2.92% & 6.58% & 10.47% \\ \hline Variance & 4.96% & 4.57% & 3.91% \\ \hline Standard deviation & 22.28% & 21.38% & 19.77% \\ \hline Cov(rA,rB) & 0.77 & & \\ \hline Cov(rB,rC) & 0.95 & & \\ \hline Cov(rA,rC) & 0.86 & & \\ \hline \end{tabular} Portfolio proportions \begin{tabular}{|l|l|} \hline XA & 25% \\ \hline xB & 35% \\ \hline xC & 40% \\ \hline \end{tabular} Portfolio statistics Mean Variance Sigma