Question

Find the rate of interest if a sum of money gets doubled in 16 years.

Answer 1

Ok so here's the solution.It's quite a simple one.Pay attention.

Let's say the amount was 100rs and it got doubled after 16years. 
So, 100rs after 16 years became 200rs.

Now this 200 = ( main amount) 100 + 100 ( the interest that we got for 16 years.)

This means that over a period of 16 years, we got 100rs. So, if we divide 100 by 16, we will get the amount that we got every year.

so 100/16 = 6.25 rs.
This is the amount you'll get every year as interest. Now to convert it to %, just think if 10rs is 10% of 100, then how what % will 6.25rs be of 100? 

Yes, you got it right.It will be same 6.25%. 

Hope it was helpful.