Financial calculation question: variable interest rate

[Dave Britten]

(07-07-2015 08:36 AM)fhub Wrote:  

(07-06-2015 02:37 PM)Dave Britten Wrote:  Corrections still welcome if anybody finds any problems with it.

No corrections necessary, your general formula is perfect!

BTW, is this (changing the insterest rate during the payment periods) a usual situation in your country?

Franz

I don't think it's terribly common. Probably just for credit cards, credit lines, and other revolving balance sort of accounts. I was offered a home equity credit line with a promotional introductory rate of 1.99% for 6 months, after which it would go to its normal rate of around 2.74-2.99%. I wanted to play with a few numbers to get an idea of finance charges over 6 months, 12 months, etc. but didn't know how to calculate a uniform payment for that situation. Thanks for your help!