Compute the efcient frontier when short sales are not allowed. Use the Solver tool in Excel (on the Data tab in the analysis section}.* To set the Solver parameters: Set the objective to be the cell that computes the {annual} portfolio standard deviation. Minimize this value. Set the \"By Changing Variable Cells" to the cells containing the portfolio weights. {Hold the Control key and click in each of the 12 cells containing the weights of each stock.)- Add constraints by clicking the Add button next to the \"Subject to the Constraints" box. The rst constraint is that the cell containing the sum of all the portfolio weights must equal one. The next set of constraints is that each portfolio weight is non- negative. You can enter these constraints individually, or check the box \"Make Unconstrained Variables Non-Negative.\" Compute the portfolio with the lowest standard deviation. If the para meters are set correctly, you should get a solution when you click "Solve." If there is an error, you will need to doublecheck the pa rameters, especially the constraints. Next. compute portfolios that have the lowest standard deviation for a target level of the expected return