Mortgage problem

[smudge]

Hi I need some assistance with this question.
You have had your offer of $800,000 on a house accepted and have arranged with the bank for a 20 year mortgage equal to 85% of the sale price. The agreement calls for monthly repayments and the bank will charge a nominal annual interest rate of 9%.
i.
If the first payment is due one month after the loan is received, what will be the monthly repayments?
After the 36th payment the interest rate increases to 10%pa.

ii.
If you choose to pay out the mortgage after the 36th payment, what is the payout figure?

iii.
If you choose not to pay out the mortgage after the 36th payment, how much longer will it take you to pay out the loan?

My workings thus far
i)$680000/(1-(1.0075/0.0075)^-240 = $6118.13

ii)Payout figure $6118.13(1-(1.0075/0.0075)^-204= $638100

iii) Stuck on this question????

Are my workings correct?
Thanks

 

[Denis]

CORRECT; good work!

Question 3 is unclear.
It is stated that the mortgage is for 20 years; so there should be 17 years left!!
I guess they mean how much longer will it take if the SAME payment is continued.
If so, you need to find the "n" (number of months) applicable to this mortgage:
$638,100 @ monthly payment of $6,118.13 at rate of 10% (.10/12)

Remember that if a^n = b, then n = log(b) / log(a).
OK?