$500 will become $1000 in 5 years find the rate of interest?	Choose the correct choice.
A) 10 %  B) 20 %  C) 25 %  D) 30 %  E) 50 %

Rationale: si = simple interest = a - p = 1000 - 500 = $ 500 r = 100 si / pt = 100 * 500 / 500 * 5 = 20 % answer is b
Answer: B