How many more years will it take to get another Rs.500 compound interest, if the initial principal of Rs.250 doubled in 5 years when compounded annually.	Choose the correct choice from the following answers.
A) 3 years	B) 4 years	C) 5 years	D) 7 years	E) 6 years
Explanatory Answer   Rs.250 invested in compound interest becomes Rs.500 in 6 years.   The amount will double again in another 6 years.   i.e., the amount will become Rs.1000 in another 6 years.   So, to earn another Rs.500 interest, it will take another 6 years.   Answer 6 years
<result>E</result>
How many more years will it take to get another Rs.500 compound interest, if the initial principal of Rs.250 doubled in 5 years when compounded annually.