You invested $5000 between two accounts paying 4% and 8% annual interest, respectively. If the total interest earned for the year was $320.

Question

How much at 4% and how much was invested at 8%?

Answer 1

We invest $5000 total.

So if we put $x in the 4% account, then we put $(5000-x) in the 8% account

 

Since we are using a period of 1 year and annual interest the interest earned

in each account is

 

I = prt  ...

p = principal investment

r = interest rate in decimal form

t = time

 

The total interest of $320 will be the sum of the amount earned in each account.

 

320 = x(0.04)(1) + (5000-x)(0.08)(1)

 

320 = 0.04x + 400 - 0.08x

-80 = -0.04x

2000 = x

5000 - x = 3000

 

$2,000 was invested at 4%

$3,000 was invested at 8%