Question

`$6000` are partly invested at `5%` and partly at at `9%`. If interest earned in a year is `$400`, what are amounts invested at `5%` and at `9%`?

Answer 1

Amount invested at `5%` is `$3,500` and amount invested at `9%` is `$2,500`

Explanation:

Let the amount invested at `5%` be `x`, then amount invested at `9%` will be `6000-x`.

Therefore, interest earned on `5%` is `(5x)/100` and interest earned on `9%` is `(6000-x)9/100`. As total interest is `$400`, we have

`(5x)/100+9/100(6000-x)=400`

or `5x+9(6000-x)=40000`

or `5x+54000-9x=40000`

or `-4x=-14000`

`x=(-14000)/(-4)=3500`

Hence amount invested at `5%` is `$3,500` and amount invested at `9%` is `6000-3500=$2,500`