Final answer:
To calculate the interest payment, find the average debt balance by adding the opening and closing balance and dividing by 2. Then, multiply the average debt balance by the monthly interest rate to get the interest payment.
Step-by-step explanation:
To calculate the interest payment using the average debt balance, we need to calculate the average debt balance for the month. To do this, we add the opening balance and closing balance of debt and divide them by 2. In this case, the opening balance is $25,000 and the closing balance is the repayment of $1,000. So the average debt balance is $(25,000 + 1,000) / 2 = $13,000.
Next, we calculate the interest payment by multiplying the average debt balance by the annual interest rate and dividing it by 12 (since it's a monthly payment). The annual interest rate is 5%, so the monthly interest rate is 5% / 12 = 0.41667%. Therefore, the interest payment is $13,000 × 0.41667% = $54.17 (rounded to the nearest cent).