In the model in Example 7.9, stock 2 is not in the optimal portfolio. Use SolverTable to see whether it ever enters the optimal portfolio as its correlations with stocks 1 and 3 vary. Specifically, use a two-way SolverTable with two inputs, the correlations between stock 2 and stocks 1 and 3, each allowed to vary from 0.1 to 0.9 in increments of 0.1. Capture as outputs the three changing cells. Discuss the results. (Note: You’ll have to change the model slightly. For example, if you use cells B10 and C11 as the two SolverTable input cells, you’ll have to ensure that cells C9 and D10 change accordingly. This is easy. Just put formulas in these latter two cells.)