At what rate percent per annum will a sum of money double in 8 years ?
Here is the answer to your query.
Let the principal amount and the rate of interest be P and R% per annum respectively.
Given : Time (T) = 8 years
and Sum of money doubles itself
⇒ 2P = P + Simple Interest
∴ The rate of interest for which the sum of money doubles itself in 8 years is 12.5% per annum.