Carol Miller went to Europe and forgot to pay her $820 mortgage payment on her New Hampshire ski house. For her 52 days overdue on her payment, the bank charged her a penalty of $23. (assume 360 days).

Question

What was the rate of interest charged by the bank?

Answer 1

I = Po*r*t = $23.
820*(r/360)*52 = 23
118.44444r = 23
r = 0.194 = 19.4 %.