Question

1. Noah has $15,000 to invest. He invests some amount at 5% annual interest and the rest at 3% annual

interest. After one year, his total interest from both accounts is $620.
How much did he invest in each account? (Clearly label which amount is for which account in your
answer. Hint: Over a one year period, annual interest is the same as simple interest.)
[6 pts]

Answer 1

He invested $ 8500 at the interest of 5% and $ 6500 at the interest of 3%

Explanation:

Let the sum invested at interest rate of 5% be X

Let the sum invested at interest rate of 3% be Y

As we know

`X + Y = 15000` - Eq (1)

`X* 5/100 *1 + Y * 3/100 * 1 = 620`

`5X + 3Y = 62000` ---Eq (2)

Multiplying Eq (1) by 3 we get -

`3X + 3Y = 45000`

Substract Eq (1) from Eq (2) we get

`5X + 3Y = 62000\\- 3X -3Y = -45000\\2X = 17000\\X = 8500\\Y = 15000-8500 = 6500`

He invested $ 8500 at the interest of 5% and $ 6500 at the interest of 3%