How do you get the effective rate ?

(Please show the formula)

= Car loans in Singapore are governed by Hire Purchase Act Borrow $50,000 at 3% for 5 years. Total interest = $50,000 X 0.03 x 5 = $7,500 Monthly payment = ($50,000 + $7,500) / 60 = $958.33 Effective rate? $50,000 = $958.33 x PVIFA r%, 5yrs r= 0.47% per month X 12 = 5.64% the convert to effective rate r = 5.79% per annum per annum (double stated rate) = 6%