What would the interest rate be if you put 2000 in the bank for 10 years and earned 1200 in interest?

1 answer

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)