Rs.100 doubled in 5 years when compounded annually. How many more years will it take to get another Rs.200 compound interest

Rs.100 invested in compound interest becomes Rs.200 in 5 years.

The amount will double again in another 5 years.

i.e., the amount will become Rs.400 in another 5 years.

So, to earn another Rs.200 interest, it will take another 5 years.