Multiple choice At what rate of interest per annum the sum will double in 16 years? 19/3% 25/2% 10/3% 23/4% None of these Reveal answer Fill a bubble to check yourself B Correct answer Explanation Let principal be P , Then S.I. = P and T = 16yrs Rate = (100 * P / P * 16) = 25/4% p.a