Answer to Question #24184 in Algebra for Faisal

Question

kyle plans to invest $6000, part at 5% simple interest and the rest at 6% simple interest. what is the most that he can invest 5% and still be guaranteed at least $320 in interset per year ?

Answer 1

For example, he invests $X at 5% simple interest and& $Y at 6% simple interest:
X + Y = 6000
0.05X + 0.06Y = 320
From the first equation:
Y = 6000 - X
From the second:
0.05 + 0.06(6000 - X) = 320
0.01X = 0.06*6000-320 = 40
Thus, we obtain X = 4000
Answer: $4000