 <translate> The question is: At what rate percent on simple interest will a sum of money double itself in 40 years?
Options:
(A) 3 1/3%
(B) 2 1/2%
(C) 3 9/3%
(D) 3 2/3%
(E) 3 6/3%
Stream of consciousness: P = (P*40*R)/100
R = 2 1/2%
 <yor> Ìbéèrè náà ni pé: Ẹ̀ẹ́dẹ́gbẹ̀ta nínú ọgọ́rùn-ún wo ni èlé lórí owó kan á fi di ìlọ́po méjì láàárín ogójì ọdún? Àwọn àyè: (A) 3 1/3% (B) 2 1/2% (C) 3 9/3% (D) 3 2/3% (E) 3 6/3% Ìṣàn ìmọ̀lára: P = (P*40*R)/100 R = 2 1/2% 