- #1

- 665

- 0

The first thing I did was to find out the total amount paid (including interest) after 20 years. I came up with 240months*$800/month=$192,000. Using this, I know know that the answer to #2 will be 192,000-ans(1). However, I seem to be making a mistake in setting up the ODE for question #1. Let S be the amount owed:

[tex]\frac{dS}{dt}=.09S-800[/tex]

The reason I set it up like so is because to me, it seemed like for each payment made, 9% of the amt. owed at that point would go towards interest and the rest would come off the current amt. I know how to solve these fine, I just need some help setting it up. Am I on the right track with my model above (I know it's not correct)?

I appreciate it.