If a certain sum of money becomes doubles at simple interest in 12 years, what would be the rate of interest per annum?

Solution (By Examveda Team)

Let,
Principal, P = Rs. 100;
Amount, A = Rs. 200;
Time = 12 years;
Interest = Rs. 100;
Rate of interest
$$\eqalign{ & = \frac{{{\text{Total Interest}}}}{{{\text{Given Time}}}} \cr & = \frac{{100}}{{12}} \cr & = 8\frac{1}{3}\% \cr} $$