A sum of money place at compound interest doubles itself in 5 years. In how many years will it amount to eight times itself?	Choose the correct choice from the following.
A) 12	B) 13	C) 14	D) 15	E) 16
100 ---- 200 ---- 5   400 ---- 5   800 ---- 5   ------   15 years   Answer: 15
<result>D</result>
A sum of money place at compound interest doubles itself in 5 years. In how many years will it amount to eight times itself?