Question

If Heather paid $692.75 in interest on a 6 year loan of $7,100. What was the interest rate?

Answer 1

Wow - that is one heck of a problem - but I think I can help.

Principal - 7,100
Interest 692.75
Time 6 years

Total paid on the loan = 7,100 + 692.75 =
$7,792.75

7,792.75 / 72 = monthly payment =
108.2326388889 =
$108.23

This calculator is a big help:
http://www.1728.org/calcloan.htm
Inputting 108.23 monthly payment 7,100 principal for 6 years equals
3.111 Interest rate
Now we'll have to see how to calculate that (Unless you just need the answer then we're finished - but I think we'll need to do some more work).

Answer 2

Thanks for the medal - but there is more work to do.