annual interest
posted by Anonymous .
you invested 12000 in two accounts paying 5% and 7% annual interest. If the totak interest earned for the year was 760 how much was invested at each rate?

12000*0.05=600
12000*0.07=840
Proportion at 5% = (840760)/(840600)=1/3
Proportion at 7% = (760600)/(840600)= 2/3 (or 11/3=2/3)
(1/3) of 12000 = 4000 at 5%
(2/3) of 12000 = 8000 at 7% 
or
amount invested at 5%  x
amount invested at 7%  1200x
.05x + .07(12000x) = 760
5x + 7(12000x) = 76000
2x = 8000
x = 4000 at 5% , then 120004000 or 8000 at 7%