The simple interest I on a principal of P dollars at interest rate r for time t, in years, is given by I = Prt. Find the simple interest on a principal of $6000 at 3% for 2 years. (Hint: 3% = 0.03) 2. Originally Posted by Patience The simple interest I on a principal of P dollars at interest rate r for time t, in years, is given by I = Prt. Find the simple interest on a principal of$6000 at 3% for 2 years. (Hint: 3% = 0.03)