8.8.Reconsider the portfolio selection example given in Section 8.2. A fourth stock (Stock 4) now has been found that gives a good balance between expected return and risk. Using the same units as in Table 8.2, its expected return is 17% and its risk is 18%. Its joint risk per stock with Stocks 1, 2, and 3 is 0.015, 0.025, and 0.003, respectively. Still using a minimum acceptable expected return of 18%, formulate the revised quadratic programming model in algebraic form for this problem. Display and solve this model on a spreadsheet.

	Stock 1	Stock 2	Stock 3	Stock 4
Expected Return	21%	30%	8%	17%
Risk (Stand. Dev.)	25%	45%	5%	18%
Joint Risk (Covar.)	Stock 1	Stock 2	Stock 3	Stock 4
Stock 1		0.040	-0.005	-0.015
Stock 2			-0.010	-0.025
Stock 3				0.003
Stock 4