ANSWER
4%
Step-by-step explanation
The simple interest formula is,
Where
• i: interest accumulated
,
• P: the principal amount
,
• r: annual interest rate
,
• t: time in years
For this problem, we are given the principal amount P = 6000, the time t = 3 and the interest accumulated i = 720. We have to find r,
Solving for r,
To express it as a percentage we just have to multiply the result by 100,
The annual interest rate of her investment was 4%.