What would the interest rate be if you put 2000 in the bank for 10 years and earned 1200 in interest?
That will depend upon how often the interest is compounded. If this is done annually, the annual interest rate I is given by
3200 = 2000*(1 + I)^10
(1+I)^10 = 1.6
1 + I = 1.048
I = 0.48 or 4.8%
The number 3200 is what you are left with after 10 years (original principle plus earned interest)