The simple interest rate on a 1150$ investment paying 202.86$ interest in 3.6 years is 4.9%
Solution:
Given that 
Amount invested = $1150 
Interest earned on investment = $202.86 
Duration of investment = 3.6 years. 
Need to determine rate of interest 
Let’s assume rate of interest in percentage be represented by variable "x"
Formula for Simple interest is as follows:

In our case simple interest = $202.86, principal = 1150 , rate of interest = x , duration = 3.6 years 
On substituting the values in formula we get 

On solving above expression for x, we get

Hence simple interest rate on a 1150$ investment paying 202.86$ interest in 3.6 years is 4.9%