This time period usually would be in years. When the amount of interest the principal and the time period are known you can use the derived formula from the simple interest formula to determine the rate as follows. T Time in Years.
R Rate of Interest per year as a percent.
Virtual Nerds patent-pending tutorial system provides in-context information hints and links to supporting tutorials synchronized with videos each 3 to 7 minutes long. Formula of SI P X T X R 100. Simple interest Principle Interest rate per time period Number of time periods. A P 1 rt where P is the Principal amount of money to be invested at an Interest Rate R per period for t Number of Time Periods.