Answer:
9% interest rate
Step-by-step explanation:
Investment = principal = $4000
Interest amount = $1080
Period, t = 3 years
Simple interest = principal * rate * time
1080 = 4000 * rate * 3
1080 = 12000 * rate
Rate = 1080 / 12000
Rate = 0.09
The rate as a percentage = 0.09 * 100% = 9%
