An investment of Rs.800 doubled in 4 years when compounded annually. How many more years will it take to get another Rs.1600 compound interest?
Choices:
A) 1 years
B) 6 years
C) 4 years
D) 5 years
E) 3 years
Explanatory Answer   Rs.800 invested in compound interest becomes Rs.1600 in 4 years.   The amount will double again in another 4 years.   i.e., the amount will become Rs.1600 in another 4 years.   So, to earn another Rs.1600 interest, it will take another 4 years.   Answer 4 years
<result>C</result>
An investment of Rs.800 doubled in 4 years when compounded annually. How many more years will it take to get another Rs.1600 compound interest?