2

I take a loan at the bank for 10 000, in 5 years I should pay back 15 000. How much was the interest rate?

I guess it's something like this: 10 000 * x^5 = 15000. How do I get x (the interest rate)?

user171517
  • 21
  • 1
  • http://math.stackexchange.com/questions/902687/bactracking-to-find-compound-interest/902693#902693 –  Aug 25 '14 at 11:07

1 Answers1

1

It depends on whether you're using simple or compound interest.

Using compound interest: $A = P(1+r)^t$ so your example would be $15000 = 10000(1+r)^5$.

This simplifies to $1.5 = (1+r)^5$, and taking the 5th root $r \approx 8.45\%$

qwr
  • 10,716