 
<translate> Tambayar ita ce: A wane kashi ne a kan riba mai sauƙi adadin kuɗi zai ninka cikin shekaru 40? Zaɓuɓɓuka: (A) 3 1/3% (B) 2 1/2 cikin dari (C) 3 9/3 cikin dari (D) 3 2/3% (E) 3 6/3 cikin dari Tsarin hankali: P = (P * 40 * R) / 100 R = 2 1/2% <eng> 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%
 