A car dealer offered $1250 cash back or 1.9% factory financing over 48 months to purchasers of selected new vehicle models. A customer financed $20,000 at the low interest rate instead of paying $18,750 cash (after the $1250 rebate). What was the effective rate of interest on the loan if the foregone cash rebate was treated as part of the cost of financing? (The 1.9% interest rate was a monthly compounded nominal rate.)

Answer= 5.27%