# Math Help - Exponential Regression and percent

1. ## Exponential Regression and percent

The question:

You make one charge to a new credit card but then charge nothing else and make the minimum payment each month. You can't find all of your statements, but the accompanying table shows, for those you do have, your balance B, in dollars, after you make n payments.

Payment | n Balance B
2 | 478.73
4 | 440.74
7 | 389.33
11| 329.99

(a) Use regression to find an exponential model for the data in the table. (Round the decay factor to four decimal places.)

$B= 520(0.9595)^n$

It looks like maybe you're supposed to find a value for $r$, so that $(1\, +\, r)(1\, -\, 0.09)$ equates to the decay factor you'd found via regression...?