Question

Jolene invests her savings in two bank accounts, one paying 4 percent and the other paying 8 percent simple interest per year. She puts twice as much in the lower-yielding account because it is less risky. Her annual interest is 3664 dollars. How much did she invest at each rate?

Answer 1

The average rate is (4%*2+8%)/3=16/3%=5-1/3%
Therefore the original investment was
3664/(16/300)=300*3664/16=68700, 
of which 1/3 was at 8% = 22,900
and 2/3 was at 4% = 45,800
Check:45,800*.04+22,900*.08=3664  yay!