Math Is Fun Forum

mom

Member

Registered: 2012-04-25

Posts: 94

finding the unpaid balance

I am just completely lost on this one. I am not coming up with anything close to what I should be.

A mortgage at 18% interest compounded monthly with a monthly payment of $500 has an unpaid balance of $5035.56 after 109 months. Find the unpaid balance after 110 months.

I used:
i=.015
n = 110
R = $500

P = [1-(1+i)^-n/i]*R

Please help.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: finding the unpaid balance

Hi mom;

I am getting a principal of 27749.23 is that close?

If so then I am getting 4611.11 as the unpaid balance.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mom

Member

Registered: 2012-04-25

Posts: 94

Re: finding the unpaid balance

Bobby,

I think so. 4611.09 was one of the options but how did you work it out?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: finding the unpaid balance

I used a difference equation and then solved that. Fancy talk for I made a formula.

I only worked to 2 decimals when working to more I get 4611.09 as required.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mom

Member

Registered: 2012-04-25

Posts: 94

Re: finding the unpaid balance

thank you

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: finding the unpaid balance

Hi mom;

I can provide the formula if you would like. I do not know how useful it would be. perhaps if we work on it together we could make it more understandable. I know the math end but the money terms I am bad at.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mom

Member

Registered: 2012-04-25

Posts: 94

Re: finding the unpaid balance

the formula would be awsome

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: finding the unpaid balance

Hi;

numberpayments = 109

interest = .18 / 12

balance = 5035.56

Plug in and you will get p = 27749.22727276801

Now you have the original mortgage.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mom

Member

Registered: 2012-04-25

Posts: 94

Re: finding the unpaid balance

I guess it worked but I had to figure out the total cost as it was not provided so the balance was unknown. I had to work off of the payments for 3 years at once a month and the monthly interest.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: finding the unpaid balance

Hi mom;

I am not exactly following you on that. I would go with the 4611.09.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mom

Member

Registered: 2012-04-25

Posts: 94

Re: finding the unpaid balance

Thank you for your help. I really do appreciate it.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: finding the unpaid balance

Hi;

You are welcome.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.