Question

Phyllis invested $9,500, a portion earning a simple interest rate of 1 1/2% per year and the rest earning a rate of 1% per year. After one year the total interest earned on these investments was $135.00. How much money did she invest at each rate?

Answer 1

let the amt invested at .015 be x
x*0.015 + (9500-x)*.01=135

Answer 2

.015*a + .01*b = 135
a + b = 9500

Answer 3

System of equations, just do what you normally do with them and solve for one variable first, then substitute it back into either equation and solve for the other.

Answer 4

.015x+95-0.1x=135
0.005x=135-95
0.005x=40
x=40/0.005
x=8000 invested @ 1.5%
9500-8000=1500 invested @1%

Answer 5

.015a + .01b = 135
.01a + .01b = 95

.005a = 40
a = 8000

Plug that back into a + b = 9500
You get b = 1500

Answer 6

Where a is the 1.5% interest, b is the 1% interest

Answer 7

But cj49 is correct too with his method

Answer 8

I just prefer Linear Algebra methods

Answer 9

@LizzyMcWire ok thank you but i dont get how you got
.01a +.01b=95

Answer 10

or how did you get that?? @cj49

Answer 11

I multiplied the whole bottom equation by .01

Answer 12

1/100=0.01
1.5/100=0.015