Even without any calculations, based on the common sense ONLY, it is clear that the most winning strategy under given conditions is the most aggressive possible investment. It is to invest 1/4 of the total to the high percent investment and 3/4 of the total to the low percent investment. So, $7500 go at the 10% investment and $22500 go at the 8% investment, giving total interest of 0.1*7500 + 0.08*22500 = 2550 dollars. ANSWER