At what rate percent per annum will a sum of money double in 16years?
Choose the correct choice from the following answers.
A) 10.6 %	B) 3.65 %	C) 6.25 %	D) 8.32 %	E) 11 %

Rationale: "let principle = p s . i . = p t = 16 yrs rate = 100 * p / p * 16 = 25 / 4 % = 6.25 % answer is c"
Answer: C