A sum of money place at compound interest doubles itself in 2.5 years. In how many years will it amount to eight times itself?  Choose the correct choice from the following
A) 7.5 years	B) 15 years	C) 22.5 years	D) 25 years	E) 27.5 years
100 ---- 200 ---- 2.5   400 ---- 2.5   800 ---- 2.5   ------   7.5 years   7.5 yearsnswer: 7.5 years
<result>A</result>
A sum of money place at compound interest doubles itself in 2.5 years. In how many years will it amount to eight times itself?