You take out a 30-year $500,000 mortgage at an effective annual interest rate of 8%. Immediately after your 12th payment, you make an additional principal repayment of $50,000, and then refinance the outstanding balance with a new 15-year mortgage at a 4% effective annual interest rate. Both mortgages require annual year-end level amortization payments. Find the amount of interest in the 5th payment of the new mortgage.