Here is the problem you need to solve:

1. On a $250,000 mortgage amortized over 30 years (360 months) at an interest rate of 11%, what would be the monthly payment?
2. On a $125,000 mortgage with monthly payments of $1,049.00 at an interest rate of 9%, what is the length of time this mortgage is amortized over?
3. On a $100,000 mortgage amortized over 20 years (240 months) with monthly payments of $1,118.56, what would the interest rate be?
4. If a mortgage is amortized over 30 years (360 months) at an interest rate of 10% and monthly payments of $2,632.71, what is the original value of the mortgage?
5. If a mortgage is amortized over 30 years (360 payments) at a 9.5% interest rate for $150,000 and there is a balloon due in 15 years (180 payments), what would be the monthly payment amount and the balloon amount? (This is a two-part question.)  

Here is the solution:

3. On a $100,000 mortgage amortized over 20 years (240 months) with monthly payments of $1,118.56, what would the interest rate be?

The question is asking us what the interest rate on this mortgage would be, therefore, we can conclude that we are solving for I in this example. The mortgage is amortized over 20 years, so we would enter 240 into N. It’s a $100,000 mortgage, so we would enter that amount into PV. The monthly payment amount is $1,118.56, so we would enter that into PMT. There is no talk of a balloon payment in this example, so we would enter 0 into FV. The answer, as listed above, should be 12.25%.

Here is the answers are listed in bolded red. 

Example #	N	I	PV	PMT	FV
1.	360	11%	$250,000	$-2,380.81	0
2.	300	9%	$125,000	$-1,049.00	0
3.	240	12.25%	$100,000	$-1,118.56	0

Part 1 : Part 2 : Part 3 : Part 4 : Part 5