The prospectus of an investment fund states that all money is to be invested in bonds that are rated A, AA, and AAA. No more than 30% of the total investment is in A and AA bonds collectively, and at least 50% is in AA and AAA bonds collectively. The A, AA, and AAA bonds have annual yields of 8%, 7%, and 6% respectively. Determine (a) the percentages of the total investment that should be committed to each type of bond, so that the fund maximizes its annual yield, and (b) the annual yield. Provide your answers as percentages, rounded to 1 decimal point (e.g. 10.0%). Use the Excel linear programming template which has been provided, or create your own LP model in Excel. Note that in order to receive full marks, your solution must be provided in Excel, and must be solved using Excels Solver Add-in.