The sum of money will be double itself in 10 years and simple interest find rate of interest? Pick one.
A) 10 % B) 15 % C) 20 % D) 25 % E) 30 %

Rationale: t = 10 years p = principle amount = x a = total amount = 2 x si = simple interest = a - p = 2 x - x = x r = 100 si / pt = 100 x / 10 x = 10 % answer is a
Answer: A