How much money did she invest at each rate?

Question

Phyllis invested $10,500, a portion earning a simple interest rate of 9^1/5% per year and the rest earning a rate of 9% per year. After 1 year the total interest earned on these investments was $961. How much money did she invest at each rate?

 

$      at 9^1/5%

$      at 9%

Answer 1

She invests H at the higher 9.2% rate (1/5=.2)

 

and L=10500-H at the lower rate of 9%. 

 

The interest she earns is

 

.092H+.09(10500-H)=961

 

solving for H as follows

 

.092H +945-.09H.=961

.002H=16

H=8000

so L =2500. 

 

They check out