Start with the partial model in the file Ch$03$ P$07$ Build a Model.xIsx. Following is information for the required returns and standard deviation

a$.$ Suppose a portfolio has $40\%$ invested in A$,20\%$ in B$,$ and $40\%$ in C$.$ What are the expected return and standard deviation of the portfolio?

Expected return: $\%$

Standard deviation: $\%$

b$.$ The partial model lists sixty six different combinations of portfolio weights $($only six of them are shown below$).$ For each combination of weights, find the required return and standard deviation.

$\backslash$table$[[w_A,w_B,w_C,{}_p,r_p,],[0\%,80\%,20\%,\%,\%,],[10\%,70\%,20\%,\%,\%,\%$s of returns for A$,$ B$,$ and C:

$\backslash$table$[[$Stock$,r_i,{}_i$