Question

Suppose you want to buy a house that costs $225,000. You have $45,000 dollars for a down payment. The bank is offering two different mortgage options.
Option A: 30-year mortgage at 4.5%.
Option B: 30-year mortgage at 4.0% with two points. The cost of the points will be rolled into the mortgage.

Answers

GPT 3.5
To calculate the monthly payments for each mortgage option, we can use the mortgage formula:

M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]

Where:
M = Monthly payment
P = Principal amount (Loan amount)
i = Monthly interest rate
n = Number of monthly payments

Option A:
Loan amount (Principal) = $225,000 - $45,000 = $180,000
Interest rate = 4.5% / 100 = 0.045
Number of monthly payments = 30 years * 12 months/year = 360 months

For Option A:
M = $180,000 [ 0.045(1 + 0.045)^360 ] / [ (1 + 0.045)^360 – 1 ]

Option B:
Loan amount (Principal) = $225,000 - $45,000 = $180,000
Interest rate = 4.0% / 100 = 0.04
Number of monthly payments = 30 years * 12 months/year = 360 months

For Option B:
M = $180,000 [ 0.04(1 + 0.04)^360 ] / [ (1 + 0.04)^360 – 1 ]

However, we need to consider the cost of the points for Option B. "Points" in mortgage terms are a percentage of the loan amount that you pay upfront to receive a lower interest rate. Let's assume each point costs 1% of the loan amount, so for Option B, the cost of the points would be 2% * $180,000 = $3,600.

Thus, the new principal for Option B would be $180,000 + $3,600 = $183,600.

To calculate the monthly payment now for Option B, we use the updated principal amount:

For Option B:
M = $183,600 [ 0.04(1 + 0.04)^360 ] / [ (1 + 0.04)^360 – 1 ]

By calculating the above formulas, you will find the monthly payments for each option.