Final answer:
To find the total interest for the 12-year mortgage, subtract the principal amount from the total amount paid over 12 years. The monthly payment for an interest-only mortgage can be calculated using the formula: (Principal * Interest Rate) / 12. The total number of monthly payments, not including the final balloon payment, is 180 months.
Step-by-step explanation:
To find the total interest for the 12-year mortgage, we need to subtract the principal amount from the total amount paid over 12 years. The monthly payment for an interest-only mortgage can be calculated using the formula:
Monthly Payment = (Principal * Interest Rate) / 12
For this mortgage, the principal is $400,000 and the interest rate is 3.45%, so the monthly payment is approximately $1,150. The total number of monthly payments for a 12-year mortgage is 12 * 12 = 144.
Therefore, the total amount paid over 12 years is $1,150 * 144 = $165,600. To find the total interest, we subtract the principal amount of $400,000 from the total amount paid, which is $165,600. Therefore, the total interest for the 12-year mortgage is $165,600 - $400,000 = $234,400.
The amount of each monthly payment for an interest-only mortgage is $1,150.
The total number of monthly payments, not including the final balloon payment, is 15 years * 12 = 180 months.