Amortization and Sinking Funds

[bubbagump]

Five years ago, Diane secured a bank loan of $310,000 to help finance the purchase of a loft in the San Francisco Bay area. The term of the mortgage was 30 yr, and the interest rate was 9%/year compounded monthly on the unpaid balance. Because the interest rate for a conventional 30-yr home mortgage has now dropped to 6%/year compounded monthly, Diane is thinking of refinancing her property. (Round your answers to the nearest cent.)
(a) What is Diane's current monthly mortgage payment?
$ 2494.33

(b) What is Diane's current outstanding principal?
$

(c) If Diane decides to refinance her property by securing a 30-yr home mortgage loan in the amount of the current outstanding principal at the prevailing interest rate of 6%/year compounded monthly, what will be her monthly mortgage payment?
$

(d) How much less would Diane's monthly mortgage payment be if she refinances?
$

i dont understand what to do after a. Which equations do i use.

 

[Denis]

Owing after 5 years:
FV of 310000 @ 9% cpd monthly after 60 months MINUS FV of 60 payments of 2494.33 @ 9% cpd monthly

OK?

 

[bubbagump]

Can you check my work for me. That answer didn't work...

Eq: A=R [(((1+(r/n))^(60))-1) / (r/n)]

For the first part I got 23381482.45
For the second part I got 188132.69
Subtracted: 23193349.76

Where did I go wrong??

 

[Denis]

Eq: A=R [(((1+(r/n))^(60))-1) / (r/n)]

For the first part I got 23381482.45
For the second part I got 188132.69
Subtracted: 23193349.76

2nd part is correct.
BUT you can't use that equation for FV of 310000; 310000 is nor a periodic payment.
Formula: 310000(1 + .09/12)^60

 

[bubbagump]

Thank you!!!