Question

Susan invests 3 times as much money at 13% as she does at 9%. If her total interest after 1 year is $1920, how much does she have invested at each rate?

a) Susan invests $800 at 9% and $2400 at 13%.
b) Susan invests $1200 at 9% and $3600 at 13%.
c) Susan invests $1000 at 9% and $3000 at 13%.
d) Susan invests $600 at 9% and $1800 at 13%.

Answer 1

Susan has invested $4000 at 9% and $12000 at 13%.

Step-by-step explanation:

Let's assume Susan has invested x amount of money at 9%.

According to the question, Susan has invested 3 times as much money at 13% as she does at 9%. So, the money invested at 13% is 3x.

The total interest after 1 year is $1920.

Interest can be calculated using the formula: Interest = Principal * Rate * Time (in years).

Using this formula, we can write two equations:

0.09x + 0.13(3x) = 1920

Simplifying the equation, we get:

0.09x + 0.39x = 1920

0.48x = 1920

x = 4000

Therefore, Susan has invested $4000 at 9% and $12000 at 13%.