Final answer:
Gustavo and Serrana will need to refinance an amount of $199,497.85. Their new monthly payment will be $1,227.45. It will take them approximately 187 months to pay off this new loan.
Step-by-step explanation:
(a) Amount refinanced:
To find the amount refinanced, we need to calculate the remaining balance on the original loan after making 78 monthly payments. Using an annuity formula:
Calculate the monthly interest rate:
- i = 5.9% / 12 = 0.00492
- Calculate the remaining balance:
- B = $870.60 * [(1 - (1 + 0.00492)³⁰ˣ¹² - 78}) / 0.00492] = $163,872.85
Calculate the amount refinanced:
Refinanced Amount = $163,872.85 + $35,000 + $625 = $199,497.85
(b) New Monthly Payment:
To calculate the new monthly payment, we use the annuity formula with the refinanced amount and the new interest rate:
- Calculate the new monthly interest rate:
- Calculate the new monthly payment:
- New Monthly Payment = $199,497.85 * [0.004 * (1 + 0.004)²⁵ˣ¹²] / [(1 + 0.004)²⁵ˣ¹²} - 1] = $1,227.45
(c) Time to Pay Off New Loan:
To calculate the time it will take to pay off the new loan with a monthly payment of $1,200, we rearrange the annuity formula to solve for N:
- Calculate the monthly interest rate:
Calculate the time to pay off the new loan:
- N = log[(1.005 * $199,497.85 - $1,200) / (0.004 * $199,497.85)] / log(1 + 0.004) = 186 months
- Round up to the nearest whole number:
- Time to Pay Off New Loan = 187 months